If someone were able to find a reliable source for the same band this work could turn into the nucleus of many wearable projects. It's hard for beginners to build electronics that are 1. small 2. comfortable 3. power efficient. These bands already take care of all of that.

There are many applications for this sort of platform. One could easily build a discreet pen testing tool which records information it sees about Bluetooth devices nearby. Or create an embedded engineering Swiss Army knife which exposes IO on your wrist to an app on your phone so you can jack into gadgets you find and poke around on the spot. Fun social applications to try too, like buying one of these for every attendee at your conference and building peer-to-peer applications on top.

Mapping out the programming interface is essential to enabling all that fun, but so is finding a reliable source for these devices.