This afternoon at SXSW in Austin, Texas, Twitter CEO Evan Williams is expected to end months of speculation by revealing his company’s plans for an advertising platform.

Williams — whose company pulled in an estimated $25 million revenue last year through search partnerships with Google and Microsoft — will be taking the stage momentarily (3pm ET) for an interview with Umair Haque of the Havas Media Lab. We’ll be updating below with live coverage.

Live Coverage and Video

[via @waynesutton]

Hugh Forrest, event director for SXSW is talking on stage. Thanking sponsors, plugging Guy Kawasaki’s Twitter panel, and holding up a t-shirt he got from Williams 4 years ago. The room is jam packed (I got here 30 minutes early and am in the front row however

Williams and Haque have taken the stage!

Twitter’s @anywhere Platform

Williams announces a new platform for integrating Twitter features for websites. It lets user follow an account (like Mashable) directly from a third-party site. Sites using it now include eBay, Yahoo, and Digg. It’s called “@anywhere”. Here are the initial partners:

Williams says that for example, users can follow a columnist right from their website. This helps solve Twitter’s “discovery” problem of finding interesting people to follow.

Williams says this should help websites gain more followers and have more people who are your fans using Twitter and talking about your content. He wants to lower the barriers to adoption of Twitter.

Williams says he thinks the platform will help news spread faster on Twitter.

On Twitter’s Business Model

Williams says Twitter’s business model is going to take experimentation – notes that Google started out by selling search services.

Williams says Twitter is still mainly focused on creating the best experience for users and businesses.

On Microsoft and Google deals, Williams says that tapping into their reach and technology is a way to bring more value out of tweets. People creating the content get wider distribution and people searching get more detailed information.

Williams says that third-party developers have plugged many of Twitter’s holes – photo sharing, link shortening, etc. The next step he says is building interfaces for specific audiences — like CoTweet and HootSuite do for businesses.

Twitter has deals with 65 mobile carriers around the world for SMS.

Williams says “we only do win-win deals” – both for users and business partners. It’s one of the reasons they haven’t implemented many revenue generating pieces to Twitter yet.

Williams says that Twitter has created a new conversation between consumers and brands (obviously).

More Live Notes

Williams says Twitter’s “140 character vision” is ease of exchange of information and being a force for good and save people time instead of costing them time.

Williams says you can take advantage of Twitter without sharing your own content. He answers the question what is Twitter by calling it an “information network” — i.e. – people who just read accounts from people and brands they are interested in as opposed to actually tweeting.

Twitter’s focused on improving the signal to noise ratio and if you’re a publisher, getting your content out to the people who care.

Williams is discussing Twitter’s structure – lots of autonomous teams who are free to experiment.

Williams says he spends about half his time thinking about product, and the other half thinking about company culture and how to scale it as Twitter grows. He wants the company try and be as open and transparent as possible both internally and externally.

Williams notes that users have defined many of Twitter’s features – like retweets and @replies. He says a core part of Twitter’s philosophy is being open to the idea of being wrong.

Williams says that Twitter sends cease and desist letters every day to malicious apps – like spammers and follower schemes.

Williams says the company has a “pretty wide definition” of what a user is — there’s a pretty broad variety of how people use Twitter, and as people consume information on Twitter, they’re more likely to get involved.

Williams says that people being able to share anything on the Internet continues to change the world.

Williams says his goal is not to get people to spend more time on Twitter (and perhaps less … sounds very Google-like)

Williams just hinted that they’ll get back to talking about business model stuff (ahem, the ad platform?!?) later in this conversation.

We’re an hour into the keynote — checking in on Twitter, it sounds like lots of people have bailed out of the room, but I can’t quite tell how many because I’m in the front. It’s admittedly starting to drag …

Williams advice for entrepreneurs: “create something you want to exist in the world.” He also notes that a lot of the most interesting companies come from outside Silicon Valley (it’s hard to think differently there).

Keynote over … no ad platform announcement. Signing off!

[img credits: Victor Hernandez / CNN]

Reviews: Digg, Google, HootSuite, Mashable, Twitter, cotweet

Tags: evan williams, sxsw, trending, twitter