Of course, they'll still work with GameCube games and possibly other Virtual Console games.
Speaking to Game Informer at this week's D.I.C.E. Summit in Las Vegas, Nintendo exec Reggie Fils-Aime clarified a minor point about Revolution controller compatibility, which still the most significant new information about the system in months.
Reggie told Game Informer that the shell (which has yet to be shown) will be required to play "traditional" Revolution games with a familiar style of controller -- you can't just use an old GameCube pad for this purpose. The compatibility with GameCube accessories is only backwards in nature. The old controllers will work on GameCube games played on Revolution, and they may be compatible with NES, SNES, and N64 games played through the Virtual Console feature.
Nintendo's stance on this seemingly minor hardware issue may indicate that the traditional controller shell will have more or fewer buttons than the GameCube controller, or that Nintendo has told developers to include some motion-sensing features even in traditional games meant to be played with the shell (which does not preclude the freehand controller's sensors). Reggie has mentioned in the past that the traditional shell will look similar to the WaveBird controller.