We've already seen several devices get major Android updates today, but apparently Google decided that it wanted to squeeze one more in. Some Nexus 4 owners are now reporting that they've received an update to Android 4.4 KitKat over the air that bumped them up to software version KRT16S. One screenshot shows that the update weighs in at 238.9MB, so if you're rocking a Nexus 4 that's still on Jelly Bean, you'll probably want to be near a Wi-Fi connection when you begin hammering that "Check for updates" button in your hunt for a KitKat bar.
Google has yet to make any official announcements regarding the start of the Nexus 4's Android 4.4 rollout, but it did tease last week that the update would be arriving "soon." As for what's included, Nexus 4 owners should see goodies like an improved phone dialer that can search contacts, translucent navigation and status bars with white icons and quite a bit more.
These updates typically go out in waves, so don't fret if you're not seeing any update notifications in your N4's status bar quite yet. Just keep one eye out for any alerts and another eye on PhoneDog and you're guaranteed to be on top of the rollout and any new info about it that gets announced.