Two more things...
First, one of my biggest usability issues with a pda is constantly stowing / retreiving the stylus when switching from key input to touch screen. What would be nice, in addition to a stylus silo, is a clip at the top of the screen that you can clip the stylus on temporarily while using the keyboard. A second option would be to have an eye hole at the top of the stylus so it can be connected to the wrist strap connection on the pda via a peice of fish line or similar.
Second thing, for those that are looking at stuffing everything into a phone factor. Instead of trying to figure out how to fabricate a case, just pick up one of those cheap 2 dollar toy cell phones they make for kids. They usually have a keypad on them hooked up to a small circuit board that makes beeps & buzz sounds. Rip out the guts, replace it with the PPZ board, and there you go. Cut out the fake display and plop in your lcd, and wire the toy keypad (which actually works) into your gpio pins or keyboard controller.