There will most likely not be an iWatch this year, the Pebble is what comes closest to it. It does have an internal ARM-based CPU and it can communicate with iOS devices over bluetooth. There are two kinds of of things you can build for it: watch faces (which don’t have any interaction) and apps.
For today’s project I want to try to put together a watch face that shows the WWDC 2013 Logo and a countdown to the keynote on Monday, June 10th.
Update June 2nd: I made the UTC offset changeable and released a build of the app via mypebblefaces.com