Android 4.4 was released with the Nexus 5 and while Google has confirmed the update will be arriving for other Nexus branded devices shortly, that leaves many other Android users to wonder. And wait. Many of the newer devices such as the Moto X will get Kit Kat, the bigger question here is when.
We haven't seen any carrier update announcements yet, however it looks like there is already a version of the update for the T-Mobile Moto X floating around. The ROM that is available is said to be a test build and there are some differences as compared to what we have seen with the Nexus 5 release. For example, the Google Experience launcher with Google Now on the left side is not included.
Another notable difference is the status bar. It was said this build still has the ICS/JB blue. The build that arrived with the Nexus 5 has white as the color for the status bar text and icons. On the positive side though, it was noted that this build "does seem to have most of the standard KitKat features, including SMS with Hangout, updated keyboard, etc."
Anyway, given this is a test build/early release, we would suggest that most users hold off and either wait for the official update, or for a leak that is a bit more up to date. Despite that suggestion though, we suspect many will be moving forward and for that crowd -- we suggest making sure you spin through the entire thread on the xda-developers forums to make sure you don't make any mistakes.
To that point, it appears as if a full wipe during the upgrade process is needed. Not to mention, the person that discovered that only reported back with word of the leaked ROM being nearly fully functional.