Hi,Tim
The Rainbowduino V3.0 is not compatible to Rainbowduino V2.0,So the firmware is also not compatible.
For now,the firmware of the rainbowduino is not updata anymore.What is using in rainbowduino V2.0 is :http://code.google.com/p/neorainbowduino/
So,for now,we don’t have a new firmware for the rainbowduino V3.0 to contral bu I2C or serial.
But our engineer is working on it.
So we will release the firmware after our engineer is finish.