Thought I do a quick test with my pcDuino and see if I could get the I2C relay board connected and working on it.
The pcDuino is really easy to get up and running on.. Like the Carambola it can be handy to have a FTDI cable handy to get console access. Once the serial cable is connected you can configure the network and generally get the board set up for connection to your network. Sparkfun have a really handy tutorial with the pin-outs, etc.
Getting Ubuntu up and running is easy, and because the pcDuino has on board flash memory, there is no need for a SD card.. kinna cool.
Connecting the I2C IO board requires 3 wires from the pcDuino, no drama, simple!