I've been thinking the same thing for a while. I even speculate on the name -- iWatch or iSiri, and even the event headline if it's called iSiri: "It's time to get sirious"

It's a totally different approach, but it's in the same domain as google glass -- wearable computing. It will be years until google glass gets to down in size to not look like a cyborg, whereas the technology for a small smartwatch seems to be in place already.