Wearable tech has taken a great leap forward lately with the Pebble Watch and Google Glass. But back in 2010, Apple technically made the first "smart watch". It was the 6th gen iPod Nano. As soon as people got their hands on the iPod, they used the clock faces and made wrist straps for it.
Apple even acknowledged those straps by issuing a software update in 2011 to add more watch faces. Unfortunately, Apple changed the shape and size of the iPod with the 7th gen and turned it into a mini iPod Touch design.
However, lots of companies big and small have been doing great things where Apple has not done (yet). In April 2012, the Pebble smart watch appeared on Kickstarter and was an instant success (I've got a pre-order coming soon, so watch my twitter and YouTube).
The Pebble does many things out of the box, including (duh) telling the time, but lets you get many notifications from your phone (and a whole lot more notifications if you're jailbroken) and now they've opened up an SDK. Now we are seeing custom watch faces, from Pokemon to The Verge logo. Even games are coming out with Tetris and Snake!
It costs $150, which is a near sweet spot for tech people. If it were maybe $125, then it'd really hit the market a lot more, but that may not be possible right now due to manufacturing costs. Honestly, smart watches were a long time in the making and now they're getting to be a lot more mainstream.
If there's one request I have for the pebble, it's Siri integration. Put a microphone and a speaker on the next one so we can at least ask something simple, like the weather. But if Apple does a watch, it'll be totally Siri-based. You'd be able to send and recurve texts, send emails, etc. all from your watch. It's the future.
Now, Google had been working for over a year on Glass before they showed it off publicly (from the verge) and what a way to show it off back at I/O in 2012. Then we learned nothing about it until they showed us this video, which finally showed how normal people would use it, and not a hipster.