As unlikely as it sounds, the Adafruit learning blog (via the Hackaday blog) has just shown off a Raspberry Pi based bitcoin miner. For those who haven't heard of the Raspberry Pi, it's a small computer on a single circuit board that was designed to be inexpensive enough to help children learn about computer science. Inevitably, hobbyists have taken the Pi to their hearts and put these tiny computers to all sorts of uses, now including mining bitcoins.
Of course, a Raspberry Pi itself has nowhere near the required computational power to effectively mine bitcoins. However, USB powered Asicminer Block Erupters do. The Raspberry Pi in this example is hooked up to a USB hub that is running four of these 333Mh/s devices. Then, via the Pi's GPIO pins, a small LCD displays the average hash rate of all the miners together (around 1.3GH/s) as calculated by the cgminer software.
According to the Bitcoin forum, these USB miners are now worth 0.99 BTC each, with approved forum members buying sets of 50 or more to sell onto end users. Therefore, that's a total of £263.78 GBP, plus roughly £60 GBP for the Raspberry Pi and powered USB hub. So there's an upfront cost of £323.78 GBP (and that's not counting the extra electronics that need putting together) to make back from mining at 1.3Gh/s.
Have you tried building a bitcoin project with your Raspberry Pi? Tell us about it in the comments.