TweetUp, a search engine/ad network that has been based on Twitter, is now changing its name to PostUp, and is adding support for both Facebook and LinkedIn. The search engine will expand to include both bios and updates posted to Facebook and LinkedIn.

"Our early experience in working with members, partners, advertisers and users has led us to see the importance of expanding what we display in search results," says PostUp CEO Bill Gross. "Many of the most prominent and respected authorities on subjects of interest to Internet users have strong preferences for one network over another and often post their comments on multiple networks. Expanding our results to include members of LinkedIn and Facebook will enable those who maintain pages on those services, either alone or in addition to Twitter, to increase the number of targeted fans or followers through one, common search engine."

PostUp says its core search algorithms and marketplace address the needs of both users and authors in a single search mechanism. "In addition to algorithms that combine a variety of factors to determine relevance, authors will soon be able to bid on keywords in a competitive marketplace very similar to what now occurs at Internet search engines," PostUp says. "This sophisticated combination of factors pushes the most relevant authors to the top of the results of users’ searches, and it enables serious members of social networks to expand their following quickly and cost-effectively."

"Market response to the PostUp concept has been extremely gratifying," says Gross. "Over 12,000 tweeters have registered over 200,000 keywords to date, and the number of impressions we are serving across our distribution network has been growing at over 100% per month. To date, we’ve served over 700 million impressions in just three months, a testament to the reach of our distribution partners."

TweetUp users are automatically included in PostUp. PostUp’s site appears to currently be down. TweetUp is still up.

PostUp says over 700 Million impressions have been served in search results on leading web sites and Twitter clients in just the three months since it launched.