Although it hasn’t been officially announced yet, it looks like Tweetdeck, the most popular of the Twitter clients, has been bought by Bill Gross’s UberMedia -- part of his Idealab business incubator in California -- and could be setting up to challenge Twitter itself.

While the deal hasn’t exactly been finalized yet, the reports -- which started circulating late last week -- suggest that, once signed off,  it will be worth US$ 30 million in cash and stock.

By all accounts, though, negotiations are well underway with terms signed that will, in effect, give UberMedia control of 20% of all the tweets sent daily, and make it the biggest Twitter client outside of Twitter itself.

UberMedia’s Ambitions

While that in itself is significant, what is probably more significant is that this is the third such deal by UberMedia since the beginning of the year alone and underlines Bill Gross’s stated ambition of becoming the biggest player in the Twitter ecosystem.

Only three weeks ago, it announced it was buying UberTwitter, a company that makes Twitter clients for iPhone and Blackberry. That was only two weeks after it had announced the acquisition of EchoFon, which produces a native Twitter client, a Facebook app for the iPhone and a Twitter iPad app.

Twitter has rapidly grown to be the most significant real-time communications medium on the planet . ... Our goal is to be the best partner to Twitter in enhancing the Twitter ecosystem, and to provide innovative ways for Twitter users to share and consume content. ,” Bill Gross said on the buyout of UberTwitter in January.

With that deal, it also announced that it was changing its name from PostUp to UberMedia. Last August, it changed its name from TweetUp to PostUp after it added Facebook and LinkedIn support.

UberMedia in the Future

Why it has changed its name to UberMedia has not been explained, but it may have something to do with the fact that, as of now, of a September list compiled by Twitter of the five most popular Twitter apps, UberMedia owns three -- including Tweetdeck, which is the most popular of those not developed by Twitter itself.

Of course, UberMedia produces other tools such as UberChannel, which gathers and filters Twitter content, and FollowMe, a tool that helps build followers. But Tweetdeck is really the jewel in the crown, and recent acquisitions do pose the question as to whether UberMedia is aiming to set itself up as a competitor to Twitter itself.

However, it is worth noting that, last week, the Wall Street Journal reported that Facebook and Google have considered buying Twitter and that “low level talks” had valued it at between US$ 8 billion and US$ 10 billion.

According to the report, the deal hasn’t gone anywhere -- at least not yet -- but it does put some perspective on the competition Gross’s UberMedia could be facing in the near future. That said, it hasn’t done too badly for a company that was founded only in 2010.