Despite being a lot of fun, Guitar Hero is likely causing a generation of kids to not learn to play real instruments. I completely suck at playing the real guitar (I am a drummer and I practiced endlessly as a tween/teen) but the game makes you feel like you know what you are doing though you clearly cannot apply your game skills to the real world guitar.
With my limited guitar abilities (Black Flag, Black Sabbath and the Misfits) I found that Guitar Hero actually made my playing worse.
Fortunately, we'll soon have Disney Star Guitarist, which trains you on the guitar by displaying Guitar Hero-like note information that applies to the frets and strings of an actual guitar. From what I gather you simply change the strings on an electric guitar to play the game. Genius.
Check out this video from Wired for a sneak peek.