From The Economist 

If you’re looking for one of the few media outlets with an official press pass into Lhasa, keep up to date with The Economist’s coverage. From the article:

Your correspondent, the only foreign journalist with official permission to be in Lhasa (which was applied for and granted well before the unrest erupted) is still allowed to remain. But in practice the city’s daily life is being controlled by troops (from elsewhere in China), foreign journalists are being barred from entering and the most repressive measures in 20 years are in force.