It's OK if your Palm OS device (http://www.palm.com/) doesn't appear in Apple System Profiler even though it is connected to the computer's USB port.
The USB connection from your computer to your USB-based Palm OS device, such as a PDA, is only active when you are performing a HotSync.
You can test whether the connection is detected by your computer, by pressing the HotSync button on the device's cradle or cable, then refreshing the Apple System Profiler window before the sync is complete.