It's pretty much here. If you've been watching the Olympics at all, you'll have seen the hype about the Nike Fuelband. It's a thin wristband that connects to your phone. An app on the phone then triggers various functions. It'll remind you to get up and stretch every hour, track your workouts, track your sleep - and it's a pedometer. Oh, and it's a watch as well.
Another company, Cuff, is targeting a different market: Women. Some of us might be happy wearing a men's watch or an activity band, but Cuff is a little chip that can be inserted into various pieces of costume jewelry - pendants, bracelets, keychains, etc. The purpose is also different - it's designed to alert all of your friends who also have Cuff to your location - whether it's to meet up for lunch or, well, for more emergency purposes.
Or how about the Netatmo June? It tells you how much UV you're getting - and pings you when you want to get out of the sun or apply more SPF 50.
The field's getting crowded and we'll see what ends up happening. Most of the wearables right now are essentially smart phone accessories, but who knows for the future?