Another entrant into the bottom end controller/hacking market. This one offers a bit more than the Arduino, it has USB connection for keyboard/mouse, HDMI and composite video, audio out, and an SD socket. It is based on an 700MHz ARM processor and has a Broadcom GPU all on a credit card sized board. It runs linux from the SD card as long as the distro has been compiled for ARM (not Ubuntu) and of course any apps need to have been compiled for ARM.
For $25 you get 128 megs of RAM, for $35 you get 256 megs of RAM and Ethernet connectivity.
It is supposed to go on sale next month, but it looks like there will be a big demand.
formatting link
An article about it
formatting link