So it's not just Google Glass (which I posted about in May 2013). Others have mentioned the patents, but I've done my own research to identify four relevant patents owned by Google.
First there was an Israeli invention, by Modu, which dates as far back as 2005. In 2011 Google purchased their patent portfolio for $4.9 million, which explains why the owner of the rights is given as Google in their Wireless telecommunication device and uses thereof.
The next three are all by inventors Gossweiler and Miller. In 2011 there was applied for what was granted, in October 2012, Smart watch including flip-up display. Here are a couple of its drawings.
Smart-watch with user interface features. Here is its main drawing.
Gesture-based small device input. The patent makes interesting reading with its talk of a virtual mouse pad. Below is its main drawing.