The factory images for Android 4.4 are now available for all recent Nexus devices. The Nexus 7 2012, Nexus 7 2013 (WiFi and 3G/LTE for both), and Nexus 4 are included. If you’re a fan of large tablets, the Nexus 10 images are there as well.
Factory images are essentially what’s pushed out via an OTA update, and are meant for reference in case something goes wrong with your device. It’s also useful for cases like this when you just don’t want to wait for Google to send out the update. Google says the updates are rolling out to users now, though we’ve yet to see them on any of our devices yet.
If you’re going to go ahead and flash Android 4.4 onto your device, keep a few things in mind. First, you do run the risk of wiping all the personal data from your device. If you have any files of pictures you haven’t saved to a cloud storage solution or downloaded manually, now would be the time for that. Also, you’ll be unlocking your boot loader, but you can always switch that back after you flash KitKat.
The good news is that Google has supported all devices, save for the Galaxy Nexus. They’ve also done so relatively quickly. In what could be a polarizing move, they’ve not yet made the kernel source available for Developers. We hope that gets rectified quickly.