Griffin has introduced the new PowerDock that is capable of charging up to 4 iPods at once. It's a perfect charging solution for music loving families, or any dude who has multiple iPods and insists on using them all. Its functionality is limited to charging for now, but it is not hard to imagine the upgrades that could occur down the line.
That having been said, you could always get yourself a JVC NX-PN7 and enjoy multiple iPod docks and playback capability starting this April. The Powerdock is expected to be released in two models: the 4 slot version featured above for $US70 this April, and a 2 slot model following for $US50 in June. [Crave]