Margit Wennmachers (pictured here), one of Silicon Valley’s leading public relations and communications execs, is joining Andreessen Horowitz as a partner.

Wennmachers, 45, co-founded OutCast Communications, whose clients include Yahoo (YHOO), Facebook and Andreessen Horowitz.

The move will make her one of a handful of women at high-profile venture outfits.

At Andreessen Horowitz, she’ll focus on bringing marketing expertise to the firm and its portfolio companies, starting in September.

“For me, it’s a chance to build a top-notch VC firm and work with talented entrepreneurs, so what’s not to like?” wrote Wennmachers in an email to BoomTown (who got off a horse in Wyoming to write this).

Andreessen Horowitz has made a big splash since it was created a year ago with $300 million in funding. Its portfolio of high-profile companies includes Skype, RockMelt and Zynga.

Wennmachers got to know both Marc Andreessen and Ben Horowitz when they hired OutCast to launch their firm last year. Andreessen Horowitz will continue to be an OutCast client.

OutCast was founded 13 years ago by Wennmachers and Caryn Marooney. It was bought by Next Fifteen Communications in 2005, but has been operated independently ever since and will continue to be.

In fact, Marooney will continue to run OutCast, which has more than 80 employees in San Francisco and New York.

Its clients reflect a breadth of Web and other companies–big and small, public and private–also including AdMob, Aliph, Amazon (AMZN), Autodesk (ADSK), Bloom, VMware (VMW), salesforce.com (CRM), Code Advisors, Cisco (CSCO), Zimbra and Netflix (NFLX).

“OutCast is the best in the business. Between VMware, salesforce.com and Facebook, they have an outstanding track record of working with the best companies and making them more valuable,” said Andreessen. “We are thrilled that one of the founders has decided to join our firm. Margit’s experience in building brands will be a big asset to Andreessen Horowitz and our portfolio.”

BoomTown liveblogged Yahoo’s “chalk talk” about search earlier today, which was an update of what the Internet giant is up to in the competitive space that includes Google and Microsoft.

Presenting at the event were Prabhakar Raghavan, head of Yahoo Labs and Yahoo Search Strategy; Larry Cornett, VP of Consumer Products; and Marc Davis, chief scientist of Yahoo Mobile.

At its HQ in Silicon Valley last week, Google put on a similar show-off, called “Searchology,” about its own latest search innovations.

And although they are clearly No. 1 and No. 2 in the search space, both Google (GOOG) and Yahoo (YHOO) are bracing for the launch a major overhaul of the Microsoft’s (MSFT) search offering, which is expected next week at the D: All Things Digital conference and code-named “Kumo.”

11:45 a.m. PDT: A delightful lunch was offered to a room full of tech reporters at the San Francisco offices of Yahoo’s outside PR firm, Outcast Communications.

But all the munching was quickly swept aside by the aggressive tone of the speech to be delivered by the normally gentle-looking Yahoos.

Apparently, top Yahoo execs want to “kill the 10 blue links.”

Yipes!

“Nobody really wants to search,” said Raghavan, describing a broken consumer experience and how Yahoo wanted to fix it. This has been a bell he has been ringing from last fall, in fact.

But we all were soon deep in the weeds of tech, as he noted that Yahoo wanted to move from a “Web of pages to a Web of objects.”

It still sounded very, very Webby.

12:01 p.m.: Soon, Raghavan started to talk about Yahoo products, such as Build Your Own Search Service (BOSS), which he says has generated almost as many daily queries as Microsoft’s whole search offering.

Snap!

Next up was Cornett, who began talking about intent and how Yahoo was trying to weave what a consumer wants in with what is displayed.

That means “helping users accomplish that goal by connecting objects in the real world.”

He trotted out Yahoo’s Search Pad offering, which is simply a way for people to keep track of their searches online, instead of on a dopey scrap of paper that the dog eats.

Cornett also showed how embedded music, video and other structured data are inserted into mostly dull search results.

Yahoo, in other words, is going to know what we want and give it to us–even before we know we want it. Sounds like my mother!

12:15 p.m.: Cornett reeled off lots of stats about its SearchMonkey technology, which is a year old.

There was a picture of a monkey with a birthday hat, natch! (See here!)

SearchMonkey, according to Yahoo, is a “framework for creating small applications that enhance Yahoo search results with additional data and structure.”

Cornett then invited up Facebook software engineer Alex Moskalyuk to talk about building apps with SearchMonkey.

Lots of tech talk that was actually incomprehensible to the reporters gathered, although they all scribbled away (I, at this juncture, chose to eat another sandwich).

Here is one line: “Originally used XPath extractor, switched entirely to hCard.”

Welcome to my world! It’s like some telephone guy talking apart a handset and explaining the guts of the device, when I am only interested in making a call.

12:23 p.m.: Next up: Matthew Hertz of Pipl.com, a people search engine built on Yahoo’s BOSS.

People search was, he said, a “deep Web challenge.” Indeed, there needs to be an easier way of finding out about a potential date online!

Actually, Pipl is a nice service and useful too, and Hertz is right that Pipl should not have to reinvent the search wheel to take advantage of all the data already available on big search services.

12:29 p.m.: Yahoo’s chief mobile geek Marc Davis was up, talking about “answers, not just links.”

Now they’re talking!

Actually, mobile is a key search arena with the increasing popularity of smart phones.

That means knowing everything from movie times to weather to flights to cheap gas prices nearby immediately.

Twittery humanity needs to know now!

Yahoo’s offering is called oneSearch. which is also a good product. It better be. “For many people in the world, their phone is the way to access” the Internet, said Davis.

12:40 p.m.: Now, the Yahoos summed up “What’s Next?”

Let’s review: Kill the blue links! Intent! Objects! Open! Mobile!

Raghavan then gave me a great joke by using the term: WOO, which is Web of objects. Apparently, they go around Yahoo talking about getting to the WOO.

It sounded naughty and I liked it.

Time for Q&A!

A question was posed about how quickly Yahoo rolls out these technologies, which are often limited in “bucket tests” of smaller groups of users.

As soon as they can, of course.

Next question was about how WOO impacts online ads. “It takes us away from a marketplace of keywords to a marketplace of intent,” said Raghavan.

That means advertisers can eventually make better ads. Oh, joy.

Then a question about when links are appropriate and when rich search should prevail.

Well, it depends on the user!

Next, a question about the currently trendy “real-time” search–a magical power that the blogosphere has, in its infinite hype-osity, bestowed on Twitter.

Raghavan called it a “buzzword” and I agreed.

Cornett added, correctly, that it should be about precision and accuracy in search, as well as serving “fresh” data. Fresh was a diplomatic word for whatever the mostly useless tweets are yammering on about at any given moment, which are most pointless.

The next question was about how soon a lot of this cool rich search data gets to the masses. Answer: Some of it is in testing and some is live systemwide.

I then asked about whether Yahoo would shove out the bells and whistles if, say, Microsoft’s new search service has a lot of the same features.

Cornett noted that Yahoo will only roll out after testing showed good results.

In other words, Yahoo will kill (or drink) no blue links before their time!

More questions about rich data, with one that makes the point that Yahoo was originally known for “curation,” which was its original business as the Web’s first truly useful directory.

It was.

1:01 p.m.: Still more questions.

Someone asked the Yahoos to comment on a recent post on TechCrunch that said the company was not developing for BlackBerry and focusing intently on the iPhone from Apple (AAPL). An exaggeration, said Davis, which was a diplomatic way of saying the story was wrong.

Blackberry users can now relax.

Gas prices through the roof?

Mortgage crisis continues?

A looming recession?

You almost have to admire Web 2.0′s fight for their right to party.

Last night, it was quite a festive mood, as a mess o’ tech press and a bunch of digital movers and shakers showed up at OutCast Communications’ Seventh Annual CEO Dinner, held in the Grand Hall of San Francisco’s historic Ferry Building.

Big clients of OutCast include Facebook and Yahoo, as well as a lot of hyper-trendy start-ups.

Here is a lovely video I did, featuring OutCast’s T.J. Snyder and Margit Wennmachers, investor Ron “Sister Woman” Conway, Yahoo (YHOO) communications czar Brad Garlinghouse and PR’s Nicki Dugan, Facebook’s Brandee Barker, VC Stewart Alsop and the incomprehensibly iPhone-addled Robert Scoble: