This Linux-based WiMax- and Wi-Fi-enabled UMPC is the smallest “full featured” computer in the world:

Processor: VIA C7-M @ 1.0 GHz
Storage: 8 GB Flash
Display: 2.8” LCD
Resolution: 640 x 480
Dimensions: 8.5 cm x 8.5 cm x 2 cm
Weight: 150 g
Battery Life: 4 hours
Connectivity: WiMAX & WiFi
Video Codecs: H.264, WMV, RMVB, MOV, FLV, DIVX