The advertising program, which Twitter calls Promoted Tweets, will show up when Twitter users search for keywords that the advertisers have bought to link to their ads. Later, Twitter plans to show promoted posts in the stream of Twitter posts, based on how relevant they might be to a particular user.
Several companies will run ads, including Best Buy, Virgin America, Starbucks and Bravo.
AdAge reveals more about how and when Promoted Tweets will work:
[Promoted Tweets] will put ads on Twitter, first in search results and later in user feeds both on Twitter.com and the myriad third-party clients that access the service, such as TweetDeck, twhirl, TwitterBerry and Tweetie, the last of which was just acquired by Twitter last week.
Initially, Twitter’s version of keyword ads will appear only on searches conducted on its website; users will start seeing those Tuesday afternoon. A single ad will appear at the top of a search. That ad is itself a tweet, and users can “re-tweet” the ad to pass it around, make the ad a favorite or reply to it.
AdAge also quotes Twitter CEO Dick Costolo, who says the ads will roll out slowly so Twitter can gauge how users respond.
There’s more discussion on Techmeme.