This is a bit orthogonal, but if you're interested in the watch form factor, TI makes a really neat watch dev board for the MSP430 that has a built-in accelerometer and support for wireless sensors.
I'm not sure whether Chronos is still in production. In comparison to this chronos is large (it is significantly larger that you would expect from the pictures) and it's radio capabilities are limited (not to mention that it does not have keyboard ;))
TI also for a short time made more advanced version with bluetooth, sane industrial design and certified radio which was quite similar to Pebble.
TI also for a short time made more advanced version with bluetooth, sane industrial design and certified radio which was quite similar to Pebble.