If you're looking for the Android 4.2.1 update to the Nexus 4 that started rolling out this morning (it's a very minor patch, at only 1.1MB), you can find it, straight from Google's servers, at this link.

The update, JOP40D, so far has one known fix: the missing month of December in the People app (Contacts.apk). Presumably it fixes other things, too - Google probably wouldn't release a patch just for a single bug, but we haven't figured out what else this patch may address just yet. That said, there is no shortage of things it could (read: should) address.

Here are all the files that have received changes as part of this update, and it's by no means just the People app:

JOP40D Mako OTA via @pof