They claim that the USB connection can be any type of device.
I tried the Keyboard sample. It definately works. No special drivers needed. Plug in the Teensy and, voilà, another keyboard.
Unfortunately, I can only get the Teensy to work with the Arduino tools if it's configured as a serial port. Thursday, I sent an email to PJRC asking for guidance but have not yet had a reply.
They also have an alternative to the Serial Monitor (HID Listen) that I like. Unfortunately, I can't get it to work with Arduino either. The Serial Monitor does work with a small caveat.
If I can get Keyboard + Arduino working, my plan is to send data directly into a waiting Excel workbook.
> Pretty good deal since you get a MCU as well.