Last Updated: November 8th, 2013
Android 4.4 is out, and that means developers and tinkerers have already started digging through the code and various APKs in hopes of porting as many updated apps as possible for use with existing devices. The first and easiest app to extract is, unsurprisingly, the clock, which also acts as an alarm, timer, and stopwatch. I've installed it on my Galaxy Nexus without any issues and only had to clear data to get rid of the pesky force close, which is completely undestandable.
Last Updated: June 2nd, 2014
After announcing KitKat and the Nexus 5 earlier today, and releasing the Android 4.4 SDK, tools, and other related goodies, Google has moved on to the next important step - source code. As announced on the Android Building forum, Android 4.4 is now trickling in, bit by bit, into the AOSP repos. If all goes well, we can expect it to complete within several hours.
Update: The source push is 100% complete.