We’re not even sure everyone managed to grab the Android 4.4.1 update that started rolling out to the Nexus 5, Nexus 4, and some Nexus 7 devices recently, and now Android 4.4.2 is being pushed out to pure-Androids. The update’s size might vary but it is a small one (sub-2MB), and it apparently brings bug fixes as well as security enhancements to the table.
The build you should expect is KOT49H and is rolling out to all Nexus devices, including last year’s Nexus 7, which didn’t get the 4.4.1 refresh. Among the changes there are also reports that this update will fix the SMS hack that was discovered recently (affecting only Nexus phones). Look for the update notification of the OTA refresh or you can manually check for its existence. It might take a day or two to reach your Nexus device, but you won’t be left out.