Well, the Android 4.4 upgrade for the T-Mobile Moto X has leaked out, but it is a very early build. Still, it shows that Motorola is working hard to follow through on promises to push updates quickly. The firmware popped up on XDA and has even been compiled into a flashable ROM (though we wouldn't suggest doing that just yet.)
The firmware has some of the KitKat improvements that you would expect, like the new version of Hangouts, and the new Google Search app. Oddly, it didn't include the Tap & Pay settings menu item. It also doesn't include the Google Experience launcher, but word has it that Google is keeping that as a Nexus 5 exclusive for now. There are also more camera improvements, which should be good news for Moto X users.