[ndom91]

Pebble are releasing a new slew of products and their arguments with rebble aside, are seemingly doing a good job so far prepping SDKs and more to easily write software for the new watches. Including leveraging the banglejs engine mentioned earlier in this thread to enable folks to write apps / watchfaces in javascript!

See: https://developer.repebble.com/docs/

[spiffytech]

Their operating system and phone bridge are also open-source. libpebble drives their wearable ring, so it's not just watches.