Charmed Technology, a startup founded by MIT Media Lab alumni, has released a CharmIT Pro, a new open-design testbed for wearable computing, based in part on a Transmeta low-power processor and Linux. Although folks have been home-brewing wearables for years (I remember early models in the mid-90's when I worked in the media lab as an undergraduate) this is one of the first commercially available wearables.
Although it's chunky, the size is actually the result of a major advantage - this system is built largely out of fairly standard parts, and it's easy for experimenters to hack, modify and adapt to new uses. Along with the fact that all information about the hardware is public (down to all the wiring), this means that it will likely foster an entire community of software and hardware developers who now can join their effort around a single basic platform. Very compelling.
Goodie... more crap to carry.