Usually the mega-band U2 doesn't get second billing.
Today, though, is the exception. In addition to the new color iPod Photo, Apple also announced a special edition iPod, the U2 in black and red. The U2 iPod retails for $349, which is $50 more than the standard 4G 20GB iPod. However, your extra $50 does get a few extras.
Beside the first-of-its-kind black face, the scroll wheel is red and the name and autographs of each of the band members is engraved on the back. Since that alone probably isn't worth $50, you also get a U2 poster and an iTunes Music Store coupon for $50 off purchase of "The Complete U2".
Otherwise, the U2 Special Edition is the same as the 4G 20GB iPod. Same size, same weight.