HTC has once again proved that it's dead serious about updating its popular flagship One smartphone. In a surprisingly early release, HTC announced that it had started pushing out Android 4.4 KitKat for the HTC One Developer Edition and HTC One Unlocked Edition.

HTC confirmed the rollout via Twitter Nov. 29.

HTC One Unlocked and Developer Edition owners - your Kit Kat roll out starts today! Let us know your favorite new additions. #KitKat #HTCOne

— HTC USA (@HTCUSA) November 29, 2013

As with all over-the-air updates, not every owner of an HTC One Developer or Unlocked Edition smartphone will receive the firmware immediately. Android firmware releases tend to happen in batches, with only a small number of lucky selectees getting an upgrade notification in the beginning.

There isn't much information concerning how the Android 4.4 KitKat affects the Sense user interface, but the fact that HTC has released KitKat so soon after its reveal on Halloween is a considerable feat in itself. OEMs typically take a couple months to tweak their specialized user interfaces to a new Android, but it looks like HTC is tackling this update cycle with a new kind of vigor.

Android 4.4 KitKat brings a number of improvements to the Android interface, but it's most notable new feature has to be its Google Now integration. Google has integrated its intelligent personal assistant into more phone functions than ever before, including the dialer, in hopes of attempting to display relevant information before it's even asked.

You can find out more about what Android 4.4 KitKat brings to the table over at Google.

HTC has also promised that all One smartphones in the United States will have an Android 4.4 KitKat update by the end of January 2014. The schedule even applies to the Verizon HTC One, which won't get Android 4.3 Jelly Bean until the second week of December, according to HTC. Carriers AT&T, T-Mobile, and Sprint have all already released Android 4.3 Jelly Bean for their respective HTC Ones.

Let us know if you've downloaded Android 4.4 KitKat for your HTC One Developer or Unlocked Edition and what changes you notice in the comments section below.