There have been a couple video preview of the upcoming Guitar Hero 3 floating around. Ive gotten all the ones I could find and put them together. Click on the play button on the videos below to watch.
Guitar Hero 3 Video Interview
Guitar Hero 3 Song - My name is Jonas -Weezer
Guitar hero 3 Song - Slow Ride
Guitar Hero 3 First look Part 1
Guitar Hero 3 First Look Part 2
