I'll be having one when you can buy one straight off, It'll be going at the other end of the USB lead to the arduino and doing things the arduino doesn't do well if at all. (Anything involving more than 2K of ram, ethernet (lets not pretend that the ethernet shield is actually usable), an RTC (OK it doesn't have one of its own but its pretty straightforward to use NTP and the internet and keep an accurate clock), plotting nice graphs from the data the arduino throws at it, logging stuff to an SD card or HDD ). Sort of a 32 bit all purpose shield......