The existence of Android 4.4.1 for the Nexus 5 was only confirmed by Google today, and here we have the update ready to go in no time. If you've got Google's latest and greatest Android phone, get ready to see some better pictures. We have the link for the OTA file (build KOT49E), so you don't have to wait on the update to reach you naturally.
Disclaimer: Android Police isn't responsible for any harm to your device - proceed at your own risk.
To get this update installed correctly you need to have the Android SDK installed and working on your computer with ADB (via a microUSB cable). This is what allows you to issue commands to your device in order to push the OTA file. Those with custom recoveries have it a bit easier, though. You also have to be running the stock Nexus 5 ROM, version KRT16M.
If you have made any system file modifications, make sure you roll them back.