On the Golden Globe awards just now, Paul McCartney presented for an award and he made a joke about Rock Band. He said, "My name is Paul McCartney or as some of you know me by... that guy from Rock Band".
I'm sure that's what some kids actually think. They think of him as the guy singing on Rock Band before they think of him as the guy who was part of the greatest rock band of all time and one of the greatest and most influential musicians of all time. At least they're learning about the Beatles though.
He also made another, not related to Rock Band joke saying, "Animation is not just for children, it is also for adults who take drugs." Another good one.
Edit: Here's the video for those of you that missed it (thanks to mf1993 for the video)