Beijing has gone up and down on this ranking for years. It came in 16th in 2010 and 9th in 2009.
This year's ranking is not really a surprise - the real news seems to be the emergence of China's second-tier cities on the list.
If rents go down due to increasing property sales, then Beijing's ranking might go down a bit in next year's survey (but lord knows what this will mean for the overall economy).