If you recollect properly, it has hardly been a month since Google started rolling out Android 4.4.3 and now, we already have Android 4.4.4 rolling out. What’s new? Everything is bug fixes and improvements under the hood.
This update has been out only for Sprint as of yet and the changelog says that it is meant to fix a major security issue. Sources say that the security bug was actually a patch to the OpenSSL which would allow a man in the middle attack. If you want to update your phone at the earliest, you will have to deal with a few things, first you will have to visit the official android site where Google has posted factory images so that you can download them and flash them.
The Nexus 4,5 and 7 have gotten this update of yet. Check them here