That's cool! The Arm Cortex-M3 is a very standard microcontroller - it supports USB! Article doesn't say what the battery chemistry is... shame the device is limited to the lifespan of a battery (I don't imagine the battery is replaceable) but that's hard to avoid! This is really cool idea and achievement.
Some relevant links:
- Arm Cortex-M3 - "Introduced in 2004 and recently updated with new technologies and configurability, the Cortex-M3 is the mainstream ARM processor developed specifically with microcontroller applications in mind."