On Sunday, February 7, The Who will play a 15-song medley during the Super Bowl's halftime show, and Rock Band will feature that same medley as a $2 download the same day (on Xbox 360 and Wii, anyway -- the PS3 version will arrive later). The identities of the songs contained in the medley will be unknown until the Super Bowl performance, but, really, they're all good.
[Update: We mistakenly identified the "S-mashup" as consisting of the 15 songs listed in the press release. It is actually a medley of unannounced songs. We apologize for the error.]