Another similar, but much cheaper board, is also coming out soon. It's called
Raspberry Pi, and you lose a bit of power (700mhz ARM11 but still has a graphics chip) but it has a much nicer price point of $25 (128mb RAM, 1 USB port) or $35 (256mb RAM, 2 USB ports, and Ethernet). The maximum power consumption is supposed to be ~3.5W.