Back in April we wrote about speculation that Twitter was in ‘advanced talks’ to buy the popular Twitter client TweetDeck, based on a story in The Wall Street Journal. This, of course, followed rumours that TweetDeck had been acquired by Twitter-competitor and eternal thorn, Ubermedia.

Earlier this month, TechCrunch quoted sources that suggested that Twitter had indeed bought TweetDeck, but no further evidence materialised.

Now, finally, the deal is done. CNN announced last night that TweetDeck has been officially purchased by Twitter for more than $40 million in a mix of cash and stock.

So… what happens next?

Specifically, what will Twitter do with this new asset? I’ve speculated before that TweetDeck as is (or really any desktop client, even Twitter For Mac) has no real place in Twitter’s infrastructure. I’m not convinced they cared about owning TweetDeck at all – they simply cared that it wasn’t owned by Ubermedia. Which makes this an expensive and rather impetuous purchase, and it’s one that I guarantee will have negative ramifications for the TweetDeck client and its fanbase.

At the very least they’ll have to re-brand it, but more likely they’ll have to make significant adjustments to the features of the software, too. I can’t see any logical reason why a Twitter-owned TweetDeck would continue to support competitors and rivals such as Facebook, LinkedIn and Foursquare, especially as all of Twitter’s other official products are very much Twitter only. That wouldn’t make sense at all.

Likewise, there’s no realistic place for Twitter For iPhone on the app store – it doesn’t make sense to have two official iPhone products as it’s simply too confusing for new users.

You can read the rest of my thoughts on how this might play out here. Bottom line: starting now, the TweetDeck many of you know and love is already (and inevitably) a thing of the past. The big question now is whether they simply modify the non-Twitter, competitive and confusing parts, or strip the wheels off of it completely. Long term, TweetDeck founder Iain Dodsworth aside, I’m not sure this is really good news for anyone.