I think the best idea is not to require users to close the apps. As
with any old Palm, or the iPhone, your goal is to get to the screen
that you need at the moment, not to manually manage memory by
remembering to close each app when you are (temporarily) done with it.
So using the aux button to get to the main screen so you can select
the next app that you need is a good way to achieve that; but if the
user launches every possible app in sequence, it should close apps as
necessary rather than running out of memory. Then you will never need
the power button hack.
