That's been tried! You can run a slightly modified version of bitcoin on a Nokia N900, and it will mine as well. The N900 performs at about a 150 Khash/second level. http://www.bitcoin.org/smf/index.php?topic=2125.msg27918#msg... For comparison, one single ATI Radeon HD 5970 pumps out about 600,000 Khash/second, or the equivalent of 4,000 N900s.