I just checked the MotionApps website and Classic, the Palm OS 5 emulator for Palm webOS, is now available for sale.
As I understand it, a demo version of Classic, which is good for 7 days, comes bundled on the device. To activate it, to plug-in your Classic serial number at the MotionApps website when you order the software to unlock the full version.
I suspect that Classic will be my first purchased third-party Palm webOS application.
Learn all about Classic over at the MotionApps website.
Here is a simple diagram of what is going on inside your Pre when you are running a Palm OS application in emulation mode in Classic.