In a statement, EA have said that they won't be bringing out any further details for the arcade basketball game NBA Jam. If you were hoping for roster updates for the various teams, or even patches to the game in general, you are out of luck.
"There have been a lot of questions about a title or roster update and we wanted to tackle this head on. Our priority for JAM on the XBOX 360 and PS3 was to deliver HD graphics and online play to round out the great gameplay that defines the franchise. For us to also include roster and title update possibilities, we would have sacrificed quality in those key areas and thus made the difficult decision not to include them."
(Thanks Pasta Padre)