Yeah, this could be some elaborate joke meant solely to screw with everyone. If not, then a life of being a douche finally caught up with him. That's karma for you.
edit: I guess you could say that he's (*Puts on sunglasses*) Dunn.
I think the police report and his death certificate are online somewhere. The rumor was probably started by a bunch of fans who wanted to believe he's still alive. It would be nice if this was just a prank, Ryan Dunn was a really funny guy. R.I.P