I highly, highly doubt WatchKit is going to make a surprise debut at WWDC this year.
Much more likely is that we'll finally see an Apple TV SDK. If there is an iWatch this year, my money is on it starting out as a "hobby" just like the Apple TV did (and is presumably about to graduate from).
Much more likely is that we'll finally see an Apple TV SDK. If there is an iWatch this year, my money is on it starting out as a "hobby" just like the Apple TV did (and is presumably about to graduate from).