I found this today. Realling interesting post from Shiv Singh, all about Twitter and their new "adwords" concept:
Something we've all been eagerly (maybe too eagerly) waiting for has finally happened. Twitter has finally launched Promoted Tweets which is a Google AdWords like program to further monetize its business. On first blush, I like the promoted tweets program unlike the third party sponsored tweets programs that I've blogged about in the past. But first let me explain how it works.Companies can buy search result terms so that their chosen tweets appear at the top of the page when a user searches for that keyword. So for example, if I were to buy the keyword "television" every time a user searched for television, he'd see my ad. My ad wouldn't be like a Google Adwords customized advertisement though. It would be a previous tweet of mine that I would have selected to appear as the ad for that search term. The promoted tweet would be clearly labeled as a promoted one and wouldn't get lost in the stream as time passes. It'll stay at the top of the page. Some other factors to keep in mind about promoted tweets:goingsocialnow.com, Twitter launches Ads, New Business Model, Apr 2010
You should read the whole article.