Twitter has reportedly done a deal to nab popular third party client TweetDeck, in an acquisition said to be worth between $40 and $50 million.

The price includes both cash and stock, and analysts are saying that the move is defensive on Twitter's part.

UberMedia were also said to be keen on snapping up TweetDeck (it even had a 30-day exclusivity period for negotiations) but, following its takeovers of other Twitter platforms such as Echofon, Twitter decided enough was enough.

TweetDeck is a UK based company that began life in 2008. It runs via Adobe's Air platform and is a popular Twitter client across multiple platforms including iPad, iPhone, Android, Windows and also the Chrome browser.

Not only can it handle your Tweets, it also integrates with Facebook, LinkedIn, Google Buzz, Foursquare, and MySpace.

Update: CNN Money is saying today (24 May) that the deal has now definitely been done, with the papers being signed on Monday.