These are what I hope for:
Opeth: It's been 3 years, and they've said they're entering the studio and aiming for a fall 2011 release.
Katatonia: Not likely, since Viva - TGCD was a 3 year wait, and TGCD - NITND was also a 3 year wait. Still, I'm hoping for a new release since in the fall.
Mastodon: It's been 2 years, and I haven't really heard much about them lately besides scoring the soundtrack for Jonah Hex which I can't seem to find anywhere. So I assume they're locked away in the studio.
Porcupine Tree: Steven Wilson is his own musical laxative. It just flows out of him. If not Porcupine Tree, it'll be his solo project, Blackfield, No-Man, the Akerfeldt/Wilson project, or something completely different.
Trivium: Fuck the haters, I love them. They're in the studio now and I think 2011 is a safe bet.
Krallice: New album is confirmed for April. They are my favorite black metal band in existence. Nobody makes black metal like they do, majestic and terrifying at once, long songs with fully-realized ideas.
There's a few.