I am most excited about iOS 4.3 because it will eliminate the need to
press physical buttons in order to operate devices. You will be able
to “paw” the display (swipe down with five fingers) to go to the home
screen. The same goes for showing the recently opened apps, music
control, orientation lock and switching directly between apps. This
will make using the iDevices heaps easier and more natural.

Touch-based interfaces are a gallant stride forward in usability and
these new 4.3 gestures are just the beginning. Humans possess innate
touch finesse. As designers catch up to harnessing these powers,
human-computer interfaces are going to become very interesting.