The Rock Band 3 Squier Stratocaster is a fully functional, full-sized, six-string electric guitar that also functions as a game controller that Fender and Harmonix have teamed up to develop.
Ever had someone ask you why you play plastic guitar instead of learning a real instrument? Now you can tell them you ARE learning a real instrument. Rock Band 3 empowers players to develop actual musical skills through the fun of Rock Band Pro gameplay. Start at Easy and work your way up through Expert on three different Pro Modes, just like you did with the plastic guitars and plastic drums.
It applies to drums (adds additional cymbals), keyboard (though it's only two octaves), and guitar, which according to promotional videos, if you play through expert on Guitar, you're playing every real note on the guitar.
From: http://www.rockband.com/zine/rock-band-3-announcements
The Rock Band 3 Squier Stratocaster is a fully functional, full-sized, six-string electric guitar that also functions as a game controller that Fender and Harmonix have teamed up to develop.