Tibet tour ban
Tibet is to be closed from 19th Feb to end of March 2012. We do not arrange Tibet Tours for foreign tourists whose Tibet travel schedule is restricted. But we accept your Tibet tour booking for your travel to Tibet after April.
It is most likely to end around mid March (once March 10-14 uprising anniversary is over). But this year is already different from the last few with serious protests in eastern Tibet (mostly west Sichuan region). The government will be watching the protests very very closely and assessing closure dates based on how serious the protest events become.
Unfortunately no-one will be able to give a 100% accurate opening date at this point (although there will be plenty of guessing and rumours!)
I would not be planning any travel to Tibet (well....T.A.R.) until at least after end of March at the earliest - there is a high chance your travel plans will be screwed up by permit problems.
More up to date Tibet travel news under this link