Android 4.4.1 is rolling out for a number of devices today, including the Nexus 5, but as with most Nexus device updates, it's happening in stages. As such, it could be a few days before you get the OTA if you choose to wait, and we all know what that's like: annoying. So, here's the Android 4.4.1 OTA for the Nexus 4.
What's new in Android 4.4.1? We know the Nexus 5's camera has been improved, but not much else, so we're working on figuring that out at the moment - expect a post in the coming days.