Veteran entrepreneur Bill Gross – a.k.a. the inventor of search engine marketing as we know it – today launched a start-up that's being called AdSense for Twitter.

TweetUp hopes to cash in on the microblogging site's stream of 600 tweets per second by filtering them – for a price, of course. Twitter members who want their messages to stand out can bid on keywords that will help lift their tweets above the virtual din. The bids could be a penny or two for each time the tweet turns up in TweetUp's search results. (Advertisers eventually will be able to bid in three ways: by impression, by new follower, or by click through to an end URL, but for right now bids are by impression only.)

Interested? The first 1,000 advertisers to sign up receive a $100 credit towards ads. What's the catch? Well, the sign-up seems straightforward; hand over your Twitter name and your bio is imported automatically, though you can edit, but it's up to you to decide how favorably Twitter users will respond. (Want some advice on using Twitter? Click here.)

Gross – the founder of the IdeaLab incubator, where TweetUp is based – founded, which in the Internet pleistocene era of 1999 pioneered the concept of paid Internet searches. Renamed Overture Services, the start-up's business model was influential to the development of companies such as Google and Yahoo, the latter of whom bought Overture for $1.6 billion in 2003. (Not surprisingly, Gross's new baby has attracted some heavyweight investors: among them Steve Case, Jason Calacanis, and Jeff Jarvis.)

TweetUp launches as Twitter holds its first-ever developer conference in San Francisco Wednesday, where the microblogging site is expected to reveal how it plans to profit from its 50 million tweets a day. (It's ruled out simply inserting ads into users' tweet streams.) TweetUp's launch also comes as Twitter has begun taking in-house applications that it has until now left to third-party developers. (For more on the contested territory, click here.)

TweetUp also will offer a free search service that will pluck out the best Tweets. A computer algorithm will rank tweets according to the writer's expertise in a particular subject and how many times followers re-tweet original messages. Popularity is also considered but is programmed to rank as least important. TweetUp has inked deals to split revenue 50-50 with websites such as,, and PopURLs, which will incorporate the TweetUp search.

"Twitter has such tremendous potential as a real-time information network far beyond what has been realized to date," Gross, TweetUp's CEO, said in a statement. "For most people, though, 80 percent or more of the tweets that fly by them when they're searching for something are useless noise. For serious tweeters, the task of attracting interested and relevant followers is equally daunting. TweetUp will change all of that."