Ars Technica:

That's right, Twitter just told its third-party client application developer community that it is no longer wanted. Existing developers will face challenges going forward as Twitter takes back the platform. The company is adjusting the terms of service that govern its APIs in order to define stricter requirements for conforming with Twitter's expectations regarding how the service is presented.

This seems like yet another Dick-move by Twitter. They wouldn’t be where they are today if it wasn’t for the enthusiasm of 3rd-party developers who created great apps like Twitterrific and Tweetie.

Speaking of Tweetie, this move is also ironic, considering that not too long ago Twitter bought it, and made it the official Twitter client for iOS and the Mac.

So basically, they let developers duke it out, then bought out the one they liked best, and ended the game for everyone. Way to go, Twitter.