Contestant on zenbroders.
Seems like this is a great start! The drawing was pretty far off on my browser (IE, brush was a good 100 px below my cursor) and live was really jumpy or non-functional, but it's still pretty awesome.
Seems really useable and awesome! The one thing I'm not sure of is what's supposed to happen with actual editing. Live chat works great, but I can't see input from another browser live. I didn't hold this against Tandem because I couldn't tell if it was because I was just logged in as myself in two windows.