That's right Rasphberry Pi has become a reality. Well the model B version did at least. That is the one that is $35 and has 2 USB ports, 256MB of memory and an ethernet jack. If you were one of the folks lucky enough to live in the UK and get one we are seriously jealous.(OK Brian is, Joe and Corey say they have enough projects.) You had to order literally in the first minute they were on sale because they sold out that quickly. There are more being made and not one but two different vendors will be taking orders for the next round. If you check out the Rasphberry Pi Project website you can find the links to get on the waiting list. (WARNING: they are doing a server migration on 3/7/2012 so there may be issues getting to the site that day.)
There is another small form factor but more expensive machine called Cotton Candy that is the size of a USB Thumb Drive. It comes with more memory, a quad core Samsung ARM processor, and wifi. The cost of these features however pushes the price up to $199. Still a good deal if you need to keep a computer in your pocket. Check out the details on both machines here.