According to a Tweet by the NBA 2K Insider, the weekly official roster update for NBA 2K12 has been delayed while the team tries to solve the recent freezing issues with the PlayStation 3 version. It seems we can now expect the next roster to be available within the next few days.
The next roster update is delayed because we are trying to resolve the PS3 freeze issue. Hoping for early next week. Sorry!
For PlayStation 3 users encountering freezes, the temporary solution that is currently being suggested is to delete your Game Data Utility files for NBA 2K12. According to this Tweet from Ronnie 2K, the issue stems from corruption of the game data file caused by an external partner and the workaround has been effective for most (but not all) users.