This one seems to make the most sense. I always take what I find on the internet with a healthy dose of skepticism until confirmed by multiple sources. Saw several google links to the same type of article sooo..
If this is to be believed.. he was off-piste (the marked course i gather) and his ski hit a buried rock which catapulted him head first onto other rocks.
The article has conflicting statements about how fast he may have been going though.
http://www.telegraph.co.uk/sport/mot...not-speed.html
"Schumacher is reported to have been travelling at up to 50mph when he slipped and hit his head on a rock in an off-piste area at Meribel in the French Alps on Sunday.
But his spokeswoman Sabine Kehm said: "Michael and the group had been skiing on normal slopes. In between red and blue slopes there was an [off-piste] area and they went into that.
He helped a friend who had fallen and went into deep snow, hit a rock and was catapulted into the air and landed head down. It was extreme bad luck, not because he was at speed."
EDIT: just found this link that seems to be more current and backs up the first article.
http://uk.eurosport.yahoo.com/news/f...47436--f1.html