I bought Guitar Hero 3 for the Xbox 360 about a week ago (I know, I am a bit late getting on the bandwagon). I find it to be a rather fun rhythm game, less exhausting than DDR (a minus, I like the physical craziness of DDR), but also a less familiar experience (a plus). I am stuck on medium difficulty until I get more familiar with the game.
Something that surprised me, though, as I was browsing the iTunes music store's best sellers a couple days ago, was that many of the songs I had been playing in Guitar Hero were on the best sellers list. After a bit further investigation, I noticed that almost the entire song list of Guitar Hero 3 is on the 100 best sellers in the Rock genre of the iTMS.
Maybe I should not be surprised that Guitar Hero can revive interest in some great rock classics-- it is a popular game and it features some great music. However, it does suggest something else... the makers of Guitar Hero now have a good argument that they shouldn't have to pay to license songs for future Guitar Hero games, because having your song in their game will create a massive increase in demand for your music.
It also means that we have entered a time when video games are influencing music listening, and not in some minor way. Digital music sales have finally surpassed retail store sales, so when the top sellers on iTMS are from a video game, that indicates a big impact. It would be fun to see some real numbers on sales for these songs.