PowerJOG for treo 2.0b1 is available here. According to the description, it looks like it can do a lot of cool things:

You can do everything SINGLED HANDED with Jog dial.
1.Choose Pop up list
2.Push Dilog window's button
3.Go to home
4.Power off
5.Push screen button
6.Launch application
7.Launch DA
8.Choose menu.
Makes me wish I had a treo.