The acquisition is a savvy one for Yahoo (YHOO), which already has a strong sports content business and stands to benefit from the additional social networking and mobile integration that Citizen Sports offers.

Below, the official announcement:

Yahoo! to Acquire Citizen Sports

Strengthens Social Strategy by Combining the Power of the No. 1 Online Sports Destination with the Web’s Most Popular Social Sports Company

SUNNYVALE, Calif., Mar 17, 2010 –As part of its ongoing commitment to be the center of people’s online lives, Yahoo Inc. (NASDAQ:YHOO) today announced it has signed a definitive agreement to acquire Citizen Sports (http://www.citizensports.com), a company that brings the world of sports to fans’ favorite social networking sites and mobile devices through innovative applications. This acquisition will strengthen Yahoo!‘s social strategy of enriching, aggregating and distributing social content from across the entire Web, and offering a highly customizable social experience.

“Yahoo! is in a unique position to combine our deep expertise in content and aggregation technology to offer a highly personalized social experience,” said Bryan Lamkin, senior vice president, Consumer Products Group, Yahoo!. “Sports has been among the earliest online categories to experience rapid social proliferation, and the combination of Citizen Sports leading products with our world-class sports experience on Yahoo! Sports is a win-win for sports fans globally.”

Millions of people across the globe use Citizen Sports’ array of social and mobile products to play fantasy sports, fill out brackets, check live scores and read up-to-the minute news on sports including football, hockey, soccer, baseball, racing, rugby, hockey and cricket. Yahoo! Sports’ content will be integrated into these products, creating a seamless experience for sports fans wherever they are. On Yahoo! Sports, users will be able to broadcast their allegiances, create or join a conversation with friends and fans and cheer for their teams through Citizen Sports’ applications. This integration will further transform Yahoo! into a more personally relevant experience, drive deeper user engagement and create opportunities for advertisers to interact with audiences in new environments.

As the #1 destination for online Sports with more than 39 million monthly unique users in the U.S.*, Yahoo! Sports provides people with the most timely, relevant and comprehensive sports news, information and programming. Citizen Sports’ network of popular applications for Facebook, MySpace (NYSE: NWS), hi5, iPhone and Android span professional, college and high school sports.

“Citizen Sports was founded with the intent to enable fans to access news, scores and fantasy games on the platform of their choice,” said Mike Kerns, founder and CEO of Citizen Sports. “We look forward to becoming a part of Yahoo! and bringing our social experiences to their 600 million users around the globe.”

Citizen Sports was founded by Mike Kerns and Jeff Ma in 2004. Since then the company has brought together millions of sports fans from around the world to enjoy sports and connect with their friends. Citizen Sports is based in San Francisco.

Yahoo! expects to complete this acquisition in the second quarter of 2010. Financial terms were not disclosed.

On my recent trip to Seattle, I visited the offices of iLike in the Capitol Hill section of that lovely Pacific Northwest city to take a video gander at one of the more interesting start ups to emerge from the social-networking arena.

The music discovery site, unlike a lot of others in its sector, has been plugging away for several years with much less funding–about $16 million from the founding Partovi twin brothers, former AOL (TWX) wunderkind Bob Pittman and a big slug from Ticketmaster (IAC)–but with a lot more impact.

Like its competitors, such as Last.fm, it has forged its popularity by focusing on linking its users with one other and musical artists via what they like to listen to.

Kind of like that old shampoo cliché: She told two friends and she told two friends and so on and so on and so on.

It’s actually quite an infectious app and also Web site, with 30 million registered users, and it’s one of the few that is useful on social-networking sites like Facebook, hi5, Orkut and Bebo.

So useful, in fact, that Facebook has selected the service as one of only two “preferred” partners, a designation Facebook announced today at its second developers conference in San Francisco.

iLike was the brainchild of Ali and Hadi Partovi, longtime Web entrepreneurs who have also worked at big companies like Microsoft (MSFT), and whose interest in music and online delivery was the inspiration for the site.

To make money, iLike has a number of businesses.

First and foremost it is essentially a lead-generator for sites like Amazon (AMZN), iTunes, Ticketmaster, and more recently, the Rhapsody subscription music service, with which it just added a somewhat restricted full-song playback offering.

And iLike has just launched an ad platform for concert promoters.

The brand itself, although focused on music right now, obviously has extension possibilities (iLike movies? iLike TV? iLike tacky theme parks?).

Most observers of iLike assume it will sell to a larger entity eventually, such as Ticketmaster, for whom the site has become a major referrer.

But the Partovis–who have sold start ups before–insist they want to build the iLike brand.

Here’s a video interview with Hadi Partovi in which we talk about all this and more, along with a tour of iLike’s offices:

Today, in yet another episode of the Web 2.0 lottery, Social Gaming Network grabbed $15 million in funding for its widgety gaming apps that are popular on Facebook and other social-networking sites.

The round, led by Greylock Partners, Founders Fund, Columbia Capital and Novak Biddle Venture Partners, will go toward expanding its offerings, which include the popular Warbook, and also its network for other developers to create and publish online games on.

SGN grew out of Webs.com, which used to be known as Freewebs.

While BoomTown often makes fun of viral apps, most of which are faddish and juvenile, the better made gaming apps actually are likely to be a real business over time, as long they remain engaging and fun to play as the classic real-life games are.

After all, who ever gets sick of Candyland?

SGN’s games are not quite that, focusing more on strategy and bang-bang that 12-year-old boys of any age so love, but, CEO Shervin Pishevar promises, with increasingly rich features and better graphics.

The business plan? Advertising, of course, especially sponsorships, as well as the sale of virtual goods and premium offerings.

SGN’s other popular online games include FightClub, StreetRace, Jetman, Text Twirl and Free Gifts. It has 1.1 million daily active users mostly across Facebook, but also on Bebo, hi5, and MySpace.

In the space, its main competitor is Zynga (here is a post and video with its founder, Mark Pincus). Naturally, the two bicker back and forth in the blogosphere about size and quality of games.

But it seems to me that there is room for both, so the fighting seems like a lot of noisy, well, game-playing.

Here’s Pishevar talking about the sector:

In order to build the necessary respect and win the mindshare of the Internet community, I recommend a recipe not unlike the one we’ve used with our TCP/IP efforts: embrace, extend, then innovate. Phase 1 (Embrace): All participants need to establish a solid understanding of the infostructure and the community–determine the needs and the trends of the user base. Only then can we effectively enable Microsoft system products to be great Internet systems. Phase 2 (Extend): Establish relationships with the appropriate organizations and corporations with goals similar to ours. Offer well-integrated tools and services compatible with established and popular standards that have been developed in the Internet community.”

–J Allard, corporate vice president of design and development for the Microsoft Entertainment and Devices Division, “Windows: The Next Killer Application on the Internet,” 1994

In February, Microsoft (MSFT) surprised industry watchers and embraced the idea of data portability, throwing its support behind OpenID, a decentralized digital-identity protocol.

This morning came the inevitable extension of that idea, the announcement of a partnership with five social networks on a new data-portability strategy. LinkedIn, Tagged, Hi5, Bebo (TWX) and Facebook have all agreed to use Mirosoft’s Windows Live Contacts API to, in the words of John Richards, director of Microsoft’s Windows Live Platform, “create a safe, secure two-way street for users to move their relationships between our respective services.“

In other words “Windows Live Messenger.” Certainly, it’s hard not to look at Microsoft’s announcement that way, given the simultaneous debut of invite2messenger.net, a new Microsoft Web site through which people can invite friends from participating social networks to join their Windows Live Messenger contact list.

“In completing this two-way street, both Windows Live and our partners have paid special attention to relationship context and privacy management in order to create the best possible user experience,” explains Richards. “We understand that just because people have a friend relationship with a contact on one social network, that doesn’t necessarily mean that they want that same relationship on another network. To preserve the context of the relationship, we are requiring that relationships be re-established in each experience with permission from the friend or contact, rather than automatically storing the data. We encourage you to visit www.invite2messenger.net to see these ideas in action, and to invite your Facebook, Bebo, Hi5, LinkedIn and Tagged friends to join you on the world’s largest instant messaging network, Windows Live Messenger.”

OpenSocial, as Google has named it, is a set of common APIs (application programming interfaces) that will enable developers to write applications for a broad range of Web sites and services without any individual customization. Think of it as Facebook CEO Mark Zuckerberg’s “social graph” but writ large.

And while some might smirk at OpenSocial’s initial roster of participants–LinkedIn, hi5, Ning, Friendster, Plaxo and Google’s own “big in Brazil” social network Orkut–it does include a few big names: business software makers Salesforce.com and Oracle. Oh, and Google. Which, as TechCrunch’s Erick Schonfeld points out, already has much of the critical mass it needs to push this effort forward: “Google already has so much data on you, depending on how many Google apps you already use. It just needs to bring everything together. … Over time, Google will connect all of these together in different ways, along with data about you from other social services across the Web, and give developers access to the social layer tying all of these apps together underneath. The real killer app for Google is not to turn Orkut into a Facebook clone. It is to turn every Google app into a social application without you even noticing that you’ve joined yet another social network.”

OpenSocial, as Google has named it, is a set of common APIs (application programming interfaces) that will enable developers to write applications for a broad range of Web sites and services without any individual customization. Think of it as Facebook CEO Mark Zuckerberg’s “social graph” but writ large.

And while some might smirk at OpenSocial’s initial roster of participants–LinkedIn, hi5, Ning, Friendster, Plaxo and Google’s own “big in Brazil” social network Orkut–it does include a few big names: business software makers Salesforce.com and Oracle. Oh, and Google. Which, as TechCrunch’s Erick Schonfeld points out, already has much of the critical mass it needs to push this effort forward: “Google already has so much data on you, depending on how many Google apps you already use. It just needs to bring everything together. … Over time, Google will connect all of these together in different ways, along with data about you from other social services across the Web, and give developers access to the social layer tying all of these apps together underneath. The real killer app for Google is not to turn Orkut into a Facebook clone. It is to turn every Google app into a social application without you even noticing that you’ve joined yet another social network.”