It would be nice to get the Arduino to talk OSC. It looks like it's tricky because the Arduino doesn't have an ethernet port, like the Make Controller.
Here are some resources that might be useful:
d.tools: Arduino support (EXPERIMENTAL)
Can Arduino send OSC directly to Reaktor etc?
[Developers] Arduino + OSC
monomeserial - Get monome to talk to a serial port
SB70 Add device connectivity to your product via 10/100 Ethernet
Procyon AVRlib - C-Language Function Library for Atmel AVR Processors
Good thing I'm learning the Make Controller first, I can get my feet wet, and then later move to the Arduino.