As previously promised, Google begins to unleash Android 4.4 KitKat for its Nexus phones and tablets. The first models to receive the update are the WiFi-only Nexus 7 and Nexus 10 tablets with more to follow soon.
http://www.notebookcheck.net/Google-releases-Android-4-4-KitKat-for-Nexus-7-and-Nexus-10-tablets.105584.0.html