I know the Mike Kulas interview has already been referenced here but what about this one over at Gamasutra?
Quite an interesting read which among other things might explain why the D3 demo system is that buggy or some things on the HUD can be repositioned and others not. I'm still annoyed by the placement of \"recording/playing demo\" almost in the middle of the screen. And no, I won't start on the 1.5 patch...