In advance of the awarding of the Nobel Prize to imprisoned Chinese dissident writer Liu Xiaobo, the Chinese government severely restricted travel for a group of liberal intellectuals who they fear may have attempted to attend the ceremony. Ai Weiwei was among those banned, though the artist recently has been a magnet for political controversy himself after a planned party to celebrate a government-mandated studio demolition ended in house arrest to prevent Ai from attending.
To me, it looks like Chinese political pressure is coming to a head for Ai and his time living with any freedom in the country may be coming to an end.