I'm in shock right now, but honestly, I don't think anyone should be that surprised. He checked into rehab last month and you know, I've got to say, shit like this happens to comedians (usually drug overdoses). I wouldn't want to be in their heads.
This is a terrible loss. I was just thinking yesterday that he hadn't been in a legit great film in a while and that I would have liked to have seen him in something soon. He was in some great movies in the 90s/early 00s. Great stand up too. RIP Robin.