Technologically, multi-touch capability exists within each app, but apparently Apple thinks registering all touches, no matter what else is going on, makes the interface harder to use. Simultaneous taps/button-presses don't seem to be part of the interface model.
I'm sure that many of the apps will get updates to their interfaces; some of these updates might allow for a fuller use of multi-touch... but I don't imagine they'll introduce simultaneous button-presses to the iPhone interface anytime soon.
I imagine that as multi-touch devices become more prevalent, the idea that the computer won't register multiple touches at all times will eventually seem old-fashioned, since it's based on having one cursor, rather than ten.
Are there any multi-touch features of the iPhone other than pinching?