> The only thing I can imagine wanting one for, if it's small and light enough, is tracking progress while I exercise.
I've been wondering about how comfortable & practical it'll be to have a larger iPhone strapped to my arm while I run. The iPhone 5 is already kinda big. If the rumors are true and Apple's screens are getting bigger, I might need to start stuffing my phone in a waist pouch and use a wrist display like Magellan's Echo series.
That would be a great opportunity for Apple to introduce a wearable that looks better & does more.
Aside from running or biking though, I have zero desire to have my email and such even more in my face than it is on my phone. Any time I'm going to interact with it for more than 5 seconds, it's going to be preferable to pull out my phone, which only takes a couple seconds anyway.