HUDuino

He’s describing it as wireless MIDI. It’s plug and play across many OSes. Large Open Source community. Very usable language. Good platform for prototyping.
Arduinos mostly limited to serial over USB (except the teeny according to the last guy). Students had major software issues. The hardware was easy, but the middleware was a pain in the arse and added a lot of latency. They tried a MIDI shield added on to the Arduino, which was not quite good enough.
The 2010 Arduino had a programmable USB chip, so could use different protocols.
There is a LUFA API to do UDB programming.
This means they could use an Arduino directly as a HID. They also have complete implementation of the MIDI spec.
The arduino still needs to be flashed over serial.
HIDuino is quite good for output, especially musical robotic. This creates standardised interface for robot controlling, though MIDI, which is actually pretty cool.
They are working on USB audio class specification. This will require a chip upgrade, as the current arduino only does 8 bit audio. They want to work on a multichannel audio device.
Fortunately, this guy hates MIDI, so they’re looking at ECM Ethernet Control Mode, which would enable OSC over USB.
this looks promising, especially for projects that don’t require the oomph of a purpose-build computer.
http://code.google.com/p/hiduino/