I can confirm that my Nokia Lumia 920 is currently installing the first over the air Windows Phone 8 updates. If you haven’t been notified of the updates don’t forget you can go to Settings -> Phone Updates -> Check for Updates.
WP Central is a great resource to find out more about what is included in the updates. I’ll update this post if anything stands out.
Here is what to expect from the process (installation and migrating data takes the longest):
- Downloading updates
- Preparing to install
- Migrating Data