For people who would like to add 5 more hard keys on their 650 using the 5-way navigator, you can by installing a freeware utility called ButtonsEx. I just tried it out and it works great. I've assigned apps to UP, DOWN, LEFT, RIGHT, and even the CENTER button (no longer alerts) and I can launch them by holding down the button.

NOTE: When you install it, you'll find ButtonsEx in your system Prefs. (There won't be an icon.)