If anyone just want to see how their Macs would run, search for "D3Sharp"
It doesn't let you actually play the game, but it is a good way to see if or machine runs Diablo well
In my case, I have a 2010 15" MBP. I can run everything on max + native resolution, averaging ~40 fps. And this is under Bootcamp.
(Btw, insert "Announces beta, doesn't invite anyone" meme here...)
But why run it under Bootcamp? I just mean Blizzard is one of the few companies that get their games running very well on both OS.