iWatch

I don't wear a watch, so when I first read about apple potentially releasing an "iWatch," I was like "who cares!"

but there more I think about it, it could be pretty cool. A small but hi res screen that acts as a mini portal to your iOS devices. People are saying it could unlock your iPhone by proximity, which seems like a novelty to me. It would have to have decent enough battery life or some other sort of charging system, because no one wants to charge another device every day. It could have siri, perhaps even a camera for FaceTime. Run widgets? Track your steps?

My question though, is what is the "secret sauce" that Apple needs to add to an iWatch that will make people go "wow, that's what I need in my life!" What is that secret sauce? Anyone?