I've been following this very very closely with my room mate who is Chinese, and fluent in the languages of China. We have been following Chinese and International news and are now pretty sure something catastrophic happened. I've narrowed it down do asphyxia of the pilots due to lack of oxygen in the cockpit, rapid decompression of the aircraft, or a bomb (terrorism).
There were two stolen passports on the plane and the people whom they belonged to both had their passports stolen a year ago or more. The tickets registered to these passports were purchased through the same agent, with the same flight paths, at the same exact time. I'm gonna call terrorism at this point.
Below is the eticket info, which can be found from many different sources.
More info and developing news can be found here on this forum
Beware, its already well over 700 posts.