Not that the Grammy awards mean much (if anything), but a couple of years ago when Dream Theater was nominated, it did cause a little bit of extra buzz for them at least. And of course they didn't win (The Foo Fighters won, blech).
But just to see them nominated again says a little bit in terms of their recognition and visibility in the music industry.
Of course this award likely won't be shown on the Awards show during Television Broadcast anyway, nor will 75% or more of the Awards anyway, which kind of says enough about how irrelevant and non-credible The Grammys to begin wthi.
Daft Punk I think is the 1 artist that received a lot of nominations, I'm sort of rooting for (and perhaps Robin Thicke per the girlfriend's fandom).
As far as whether Dream Theater will win? I'd be surprised, especially considering Black Sabbath are also in this category. There's a much better chance Yes gets into the Rock and Roll Hall of Fame next Spring, than Dream Theater winning this, but I guess I will have to at least pay attention to the results when they happen in a few months.
http://www.grammy.com/nominees
13. BEST METAL PERFORMANCE
T.N.T.
Anthrax
Track from: Anthems
Label: Megaforce
God Is Dead?
Black Sabbath
Track from: 13
Label: Vertigo/Republic
The Enemy Inside
Dream Theater
Track from: Dream Theater
Label: Roadrunner Records
In Due Time
Killswitch Engage
Track from: Disarm The Descent
Label: Roadrunner Records
Room 24
Volbeat Featuring King Diamond
Track from: Outlaw Gentlemen & Shady Ladies
Label: Republic Records