HTC via its Twitter account has revealed that it has started rolling out Android 4.4 update for HTC One developer edition and the unlocked version in the United States starting this week. The update is now rolling-out over-the-air and you can check for it manually by going to Settings << About Phone << Software updates.
The Android 4.4 update for HTC One includes Sense 5.5 user-interface and not the Sense 6.0 UI, which is rumoured to debut with HTC One successor. Thanks to KitKat goodness, you can expect to see the inclusion of cloud-print support, immersive mode, faster multi-tasking, closed captioning, Easy home screen switching and more your HTC One after the update.
The other versions of the HTC One are expected to get Android 4.4 update around January 2014.
To remind you, HTC One Google Play Edition was the first HTC One variant of get KitKat update, which recently started rolling-out for the phone.
Take a look at the features of Android 4.4 KitKat update of HTC One developer edition and the unlocked versions: