There have been a plethora of "smart watches" that can control non-iPhone products but now Eric Migicovsky - who is behind a number of other smart watches decided it was time to let iPhone users in on the party.
This one, named the Pebble controls both Android and iPhone. It has an e-paper display, bluetooth, an Accelerometer, and a 7+ day battery life to name a few features. It's not touchscreen, so those of you with iPod Nano watches are still hip. It will have an open SDK which I have no doubt will lead to really cool uses of the technology.
This project started out asking for $100k in funding and got that within 2 hours. By days end it was up to $500k so it's safe to say the project is under way. Check out the link to Mashable for a cool video and more info.