Google just posted the new factory images of Android 4.2 (JOP40C) for the Nexus 4, Nexus 10, and Nexus 7 w/HSPA+. If you own or are going to be the owner of one of these devices, you will want to download these files and store in a safe place. You never know when you may need to restore your device to 100% stock after tinkering for too long. We have generic instructions for flashing factory image files here.
Download: Nexus 4 | Nexus 10 | Nexus 7 (HSPA+)