Youtube has a bunch of recent John Mayer and Phil Lesh shows:
Ok ok that was a troll post by me. I was actually echoing some of the commentary here on TGP when those videos first came out. Mayer is apparently a very polarizing musician. I happen to think he's a fantastic and original player, hardly the blues hack some think he is.
What's funny is that if you listen to the videos very rarely does Mayer even play anything minor pentatonic. He creates some really beautiful passages and obviously has a very strong grasp of theory.