License: Thanks, good catch!! it's "MIT License"
This was clear in Google Code -- but I guess this info was kinda lost when I exported to GitHub (?). I just created a LICENSE.txt file.
V-USB: Ah yes, the software-only version. I think the USB descriptors returns if one supports a specific USB speed. V-USB is low-speed only and 1.1 compliant only. If the plan is on emulating a normal Wacom tablet, I am affraid that any change to the USB descriptor will make the Wacom driver bark (Wacom's drivers are super-picky). Now if the plan is to build a generic HID tablet or maybe one of those TabletPC consumed by non-Wacom-built drivers, you might actually be in luck. I wouldn't use a device without a real hardware USB (with USB 2.0 signaling support). I mean so many inexpensive devices are available with this capability. I wouldn't want to slow down a user's USB bus with a 1.1-only device on the bus. (USB: it won't slow down the USB devices transmission speed, but I fear it might affect the USB polling timings -- but I am not 100% sure of that).
I don't think the USB speed should matter much. At least the Linux drivers only check for USB VID and PID (and I somehow hope the Windows driver does the same...).
A generic Tablet interface is a good idea but I have no idea how to write Windows drivers
Also I really want to sometimes try to implement my own version of a Wacom tablet using a few multiplexers, opamps and an fpga (need to learn a lot more about how this things work though before I can even attempt). And if I use a non-commercial license I can even publish it as some form of "Open Hardware Tablet" without getting myself into some patenting troubles ^^