If the iWatch has the ability to remotely turn on the ignition of my Lexus, then I'm sold.*** (not really hard to do, because many electric/hybrid cars like the Prius can already do this)
This is just one example of how a smartwatch, a device which one would constantly be wearing on their skin, could facilitate soooo many everyday tasks. Heck, why even bother grabbing your iPhone from your pocket (or fumbling for it in your purse, backpack, manbag, waist holster), when many such tasks (e.g. remotely starting your car, or remotely turning on your home's alarm security system, etc) could be done by the flick of your wrist, the push of a single button, or a succinct verbal command directed onto your wrist.
There are certainly lots of possibilities.
*** and if someone mugs me in order to grab the iWatch from my wrist, thinking that is his ticket to stealing my car, then he would realize that HE is not able to start my car simply by barking "Siri start the engine!" The Apple iWatch should be smart enough that the voice recognition command is like a vocal password unique to its owner. It only recognizes MY voice, and only recognizes MY commands. Now that would be a device worthy of the name "smartwatch". Probably a few years away until we see this as a reliable feature.