Do I need a transit visa for Beijing China? Flying to Dubai via Beijing and back in May 2012.

If you don't leave the airport transit area and the whole transit will be done within 24 hours , you won't need a visa. So, you don't need a visa on the way to Dubai but need one on the way back since you'll go outside the airport. You can either apply for a transit visa in advance or apply for a transit stamp at the airport upon arrival.

Just posted this above in response also - we flew from Bangkok to Vancouver with Air China last week (28 Sept/11) and had a 9 hour lay over in Beijing.
My husband and I were allowed to leave the airport for up to 24 hrs. We had no visa.
It was very easy, no problems at all. We travel on Canadian passports. We had time to catch the train into Tiananmen square, visit the Forbidden city, and back to the airport with a couple hours to spare.

Just posted this above in response to another query also - we asked at the desk when we arrived if it was possible to leave the airport and there was no problem at all. We had no transit visa. Getting out of the airport took less than an hour. About another 45 mins into the city centre by train. Definitely worth doing rather than sitting at the airport all that time.