MCV reports that Realtime Worlds' MMO, APB, will launch its crime-infested sandbox next March. The game will be distributed on PC and Xbox 360 by EA Partners, the same division of the publishing behemoth handling Rock Band and Left 4 Dead. This would make APB just the second MMO to hit the Xbox console and the first "next-gen" game to do so, following the 2006 re-release of 2003's Final Fantasy XI.
We're currently trying to follow up with Realtime Worlds and EA for confirmation. We'll update if we hear anything back.
Update 2: Realtime Worlds: "Realtime Worlds have only ever announced a Q1 2010 launch window. Any other dates you may see are either assumptions or speculations based on this."
Update: EA reiterated that "early 2010" is its release window, also "there are currently no plans for a 360 version."