For what it's worth, the N900 can "recognize" when a swipe comes from the outside of the bezel inwards. There's no reason that we can't have bezel-gestures like the PlayBook or webOS do - it just needs to be written properly.

Example -

Enter "edit mode" on the desktop and slide your finger from off the display onto it in left or right and the workspace will change while staying in edit mode. PR1.2's hildon-home allowed swiping down to bring up hildon-status-area, it's since been modified and lost.