Yesterday Apple released beta 4 of the iPhone 3.2 SDK. Initially nothing seemed very different from the previous beta, until today when users located new gesture references.
Deep within the gestures folder of the new SDK, two new types of gesture commands have been found. The gestures are not currently present in the iPhone 3.1 SDK and are labeled 3Tap.plist and LongPress.plist.
In short, 3Tap.plist means a new 3 tap gesture and LongPress.plist simply indicates a long press gesture command. It is likely that these gestures will show up in the next iPhone firmware 3.2, currently at 3.1.3, or may even debut in a 4.0 release.