I really, really hope Deftones are on it, but preferably not in last year's Motorhead slot, otherwise I'd miss most of their set every day while loading out (if I do the tour again, that is, I probably won't know until April or so). I was thinking the other day that Behemoth would be a good fit, since a new album should be around the corner and they did Mayhem '09. I know they haven't done Mayhem before, but Dillinger Escape Plan should have a new album out around then, and have done Warped a bunch in the past, I don't know if they'd be interested in making a jump to Mayhem or not. They tend to shy away from super-metal lineups sometimes and do different things.
Stop by the Metal Blade tent at Mayhem this summer, dammit