Alerting msdania -- I think I just saw John Mayer play "Message in the Bottle" with Sting in The Police reunion performance during the Live Earth Concerts for a climate in crisis.  Am I right?

Here's my favorite performances so far:

Duran Duran performs "Planet Earth" for Live Earth

Spinal Tap reunites for Live Earth
with an Army of Bass Players (basically they made anyone with a bass guitar backstage come out and play)