Do games like "Guitar Hero" help to learn guitar?
"The further you get into technology, the further you go into gaming. That's the general rule." — Nick Johnson

Technology is great. It's what has allowed us to be the ultimate power in this planet.
Gaming is great. It's what allows us to have fun waging war and being a**holes without feeling (too) bad.
No.
You won't learn to play guitar from console games. It's just not what they are designed for. A game is supposed to be fun, not to teach.
Of course, this does not mean that learning cannot be fun too, because I would be lying if I claimed such a thing. The problem is that it's one thing to expect learning to be fun than to expect the fun to teach something.
I know, I know. Some of you might be yelling at the screen right now, but hear (read) me out:

The "guitars" used have no strings.
You cannot play chords.
No fingerpicking or pick technique.
You don't learn to coordinate your fingers.
No arpeggios.
No nothing.
Yes, I know others might be thinking that you can benefit from moving your fingers in a similar fashion. That might have some use, of course it's better than doing nothing, but why not play the real thing?
Don't get me wrong: if you want to play, that's fine, go ahead, but don't expect to learn. Instead, how about buying a real guitar for just about $50 or $60 more than the game?