According to reports, Samsung has temporarily halted the TouchWiz UX update for the Galaxy Tab 10.1. No specifics as to why were given, but more than likely they discovered a fairly major bug that required this drastic action. There has been no word given by Samsung yet of how long it will take to fix the issue. We will inform you if any more details emerge, and when the update starts rolling again.
Source: GalaxyTabForums.net via AndroidPolice