We wouldn't recommend speculating too much here, but a patent Apple filed back in October 2007 has surfaced, describing a "movement-based interfaces for personal media device." If that's not enough of an explanation, in a nutshell it's for interacting with a device by tilting and shaking. Chances are this is just for accelerometer-based commands like switching to landscape, steering virtual go-carts, and undo
-- but hey, if the gang at Cupertino devise a way to control an iPhone entirely by waggle, we'll be more than happy to witness a demonstration.
[Via Unwired View