Twitter has acquired TweetDeck, sources close to the deal say the transaction should be announced within the next few days. The price tag is around $40-$50 Million and this purchase price includes both cash and stock of Twitter.

In February we reported that an acquisition of TweetDeck by Bill Gross’ UberMedia was all but done, in the $25 – $30 million range. And that deal was in fact all but done. But Twitter quickly provided an unsolicited counter offer, and TweetDeck was in play again.

This move is big for Twitter no doubt and will keep the Twitter family growing. This deal is defensive for Twitter, say all the sources we’ve spoken with over the last couple of months. They simply couldn’t allow UberMedia to have so much market share in this space. The company has acquired UberTwitter, EchoFon and a number of other Twitter-related startups. Adding TweetDeck to the UberMedia stable of products would give them too much leverage over Twitter, say our sources.