One of the core issues with most multitouch devices is that they are WAAAAY to small and low resolution to manage large sets of information all at once. They need a widget to conveniently contain and access information and applications on the fly...much like Spaces on the Macintosh or that Aero thing in Vista.
For a bunch of reasons, scaling the background (like pptPlex) is a convenient way to do this. As tasks requirements change, it might also be useful to reorganize background "plates".
Check out this early test from Infostrat. Might a controller, sort of like this like make an interesting solution?
What about if the background were thought of as a sphere so that the top of the screen seamlessly mapped to the bottom...
Any thoughts? Comments welcome.