Idle speculation: The 911 call came in at 12:21, which is when you'd expect a Michael Jackson to be first getting up. Someone might checked on him when he didn't get up, and found him in a state of not breathing. This is a common drug OD scenario.
You could be on to something. The rumor flying around the twitterverse is that it was due to sleeping pill OD.
Sounds kind of like what happened with Elvis. If he dies, he is going to knock poor Farrah and her long battle off the headlines. This is too weird.