SiliconANGLE blogger John Furrier found a supersweet television ad that eBay Internet phone unit Skype is running to goose its brand (see below).

The once-hottest-ever start-up–touted up and down Silicon Valley for its explosive growth back in 2003–is still a major global brand with a massive 405 million user accounts at the end of 2008.

In fact, Skype’s size makes media-overhyped Twitter seem, well, twee, by comparison. Twitter had only 9.8 million unique visitors in February, up impressively from 6.1 million in January.

But the hot-or-not comparisons between the two are interesting to think about.

First, as with Twitter, few pay anything for Skype’s communications services–essentially, it lets consumers make voice and video calls between computers or to other phones via voice over Internet protocol, or VOIP.

Second–although no one seems to care when it comes to Twitter as yet–monetization issues dog Skype, which actually had $550 million in revenue last year (see chart).

Still, right or wrong, many investors argue that Skype was a very bad acquisition for eBay (EBAY), which paid $2.6 billion for it in 2005 and there are consistent rumors that eBay is looking to unload the service.

That’s why it recently announced a plan to enter the corporate market, presumably to give Skype more heft.

Much like, for example, Twitter’s recent partnership with a new ExecTweets service, a compilation of business figures tweeting, which is sponsored by Microsoft (MSFT).

Lastly, of course, Skype is trying new branding to make it seem less shaggy, such as the video below, is part of that push.

As for Twitter, it remains as cute as ever and shows no signs of changing to try and please anyone.

Yet.

Here is the Skype ad:

And, as an added plus, here’s Twitter’s co-founder Ain’t-Nobody’s-Biz Stone in an interview about Twittermania, which is preciously what it degenerated into on San Francisco’s KQED Public Radio today:

And don’t worry, Twitter users: You won’t be getting come-ons for Vista in your Twitterstream. Not yet, at least.

The program that Twitter has rolled out today–something called ExecTweets–is a fairly cautious step into marketing, and that is certainly by design. But it does give a you a good sense of what Twitter thinks it can do with its buzzy, fast-growing and almost revenue-free product.

Today’s news: Microsoft (MSFT), via its Federated Media ad network/platform/agency, is sponsoring a page that collects Tweets from various executives. Twitter will get an undisclosed payment for giving the site its stamp of approval and for promoting the site on Twitter itself. Federated says it plans on launching similar programs on Twitter with other clients.

Soon, most likely today, Twitter users will start seeing promotions for ExecTweet on the main Twitter login page, and in the little box that Twitter just started featuring on profile pages. The one that looks like this:

As advertising goes, this is pretty innocuous. Hard to imagine even Twitter’s most anti-advertising adherents having a big problem with this one. But it’s also hard to imagine that many people will see the ads at all since the majority of Twitter use happens off the site, on mobile apps like Twitterific for Apple’s (AAPL) iPhone and desktop clients like Tweetdeck.

And it’s hard to imagine that many folks will want to use ExecTweet, period: The whole joy of Twitter is seeking out and finding specific people you find interesting–not just a mass of people whose common thread is that they’re “executives.”

I already follow AOL founder @stevecase, for instance, who’s prominently featured on ExecTweet right now. But I don’t imagine I’ll want to pay attention to others who show up on ExecTweet simply because they’re on ExecTweet.

And note that nothing about ExecTweet required Twitter’s OK: The company’s open API model allows users to repurpose its data for their own Twitter apps, and countless entrepreneurs and engineers are doing just that.

But there is something to be said for branding campaigns launched with Twitter’s approval and participation. Figuring out exactly how much that will be worth, and what it will eventually look like, will likely take Twitter and its ad partners a while to figure out. But now they’re starting. Finally.