Earlier this week, Twitter announced and deployed its new advertising model based on Promoted Tweets in search results on Twitter.com.

Biz Stone, Twitter’s CEO and founder, is obviously being very careful about commercializing Twitter. As he states:

Stubborn insistence on a slow and thoughtful approach to monetization—one which puts users first, amplifies existing value, and generates profit has frustrated some Twitter watchers. Believe me, when your name is Biz and you’re a co-founder of Twitter, it also means putting yourself at the mercy of folks like Stephen Colbert who hit home runs with lines like, “So, I assume that ‘Biz’ in ‘Biz Stone’ does not stand for ‘Business Model’.”

Twitter’s new advertising model reflects this slow and thoughtful approach. Twitter extends well beyond Twitter.com through its APIs and services like TweetDeck, Brizzly, and Seesmic, among others. Also, user’s own streams are more important to them than search results on Twitter. So, putting sponsored tweets on search results on Twitter.com is quite conservative.

John Battelle seems to think that Promoted Tweets will also be appearing in user’s Twitter streams, but I can’t see any evidence of this. It would make sense as a next step, but would also introduce something new to Twitter — tweets from someone you didn’t want to follow.

Twitter is relying on “resonance,” which is their buzzword for quality. It is based on nine dimensions, as Dick Costolo described it:

Twitter will measure what it calls resonance, which takes into account nine factors, including the number of people who saw the post, the number of people who replied to it or passed it on to their followers, and the number of people who clicked on links. If a post does not reach a certain resonance score, Twitter will no longer show it as a promoted post. That means that the company will not have to pay for it, and users will not see ads they do not find useful, Mr. Costolo said.

Ultimately, Twitter needs to survive. While I initially thought a white-label business-to-business offering would be Twitter’s first commercial move, this new ad search  model won’t be their last.