From Dwayne Fujima:
This is a simple hack that maps one of the 4 app buttons to act as a power on button without launching the associated app.
This hack is for those of you with cases that make awkward access to the power button, or broken or difficult to use power buttons. You can turn on your Palm by pressing the alternate power button, and then when your Palm is on, pressing the button again will launch the associated app. You have the option of mapping the button to both power on or power off your Palm.