MacRumors today details a series of patent applications filed by Apple which deal with motion and the iPhone. The first patent details movement as an input method. The example they use is flicking the phone to step through contacts. The iPhone already uses such an interface for "shake to shuffle" music as well as apps like Urban Spoon use this type of gesture to pick a random restaurant in the area.
Next, Apple details an idea of making the lettering/ GUI choices bigger while the iPhone detects it is in motion. This would make the iPhone easier to use while jogging or (hopefully not) driving. The example they cite is the contact list which enlarges as it detects motion (image below).
Perhaps most interestingly, however, a reader points out that Apple has a front facing camera on the patent application, meaning that we’ll hopefully see this feature for video chatting in an upcoming model, maybe even in June? It is labeled "180" in the image below right above the earpiece.