General Mobile has unveiled a wristwatch handset called GM500 at the CeBIT event. Currently this is a world smallest GSM-phone

The specs of the GM500 Mobile Watch:

• GSM/GPRS 900/1800/1900 MHz
• Display - 1.5” OLED touchscreen
• WAP
• Interface - Bluetooth and USB
• Media player (MP3, MPEG4, 3GP)
• Voice recorder
• 128 MB of onboard memory
• Li-Ion 400 mAh battery
• Talk time - 120 minutes
• Standby time - 80 hours
• Dimensions – 58.1×44.2×16.4 mm
• Weight - 142 g.

Source:http://www.mobile-review.com/fullnews/main/index_eng.shtml