They have switched to Scala ...

Both the Scala EPFL site and Lambda the Ultimate are talking about this cool information: the Twitter team has turned to Scala recently ... good choice :))

If you follow the links above, you'll find (amongst other things) a nice presentation from Alex Payne (there's another older one here) as well as an interview of the Twitter team (interviewed by Bill Venners).

By the way, there's a rumor about a potential acquistion of Twitter by Google !!! In case it's effective, I hope that Google will continue pushing a lot for Scala (note that Google "have" Lex Spoon already) and develop some cool tools/libraries based on Scala ... Well... I've a first suggestion: the Scala version of GWT i.e. you write everything in Scala and you get your stuff running on a JVM for the server-side and in javascript or even in scalascript (!!!) on the client-side :))