The hits keep coming from Android 4.4, and the latest one is the default android email app (you know, the one that isn't Gmail). Android Police alumnus Ron Amadeo posted the updated APK to his Google+ account early this evening, and we've mirrored it for you below. If you use the Email app (and you haven't found a better alternative on the Play Store), you'll want to check it out.
Above: Android 4.4. Below: Android 4.3.
The interface has been given a full update to make it look very, very similar to the updated Gmail. You'll get the same white Holo interface, the same icon and action bar, and the same slide-out menu, plus the swipe gestures for refreshing and deleting mail. Unfortunately the core functionality hasn't changed that much - you're still limited to the basic POP/IMAP/Exchange setups, with the same nearly universal settings and options.
Aside from the facelift, there isn't a whole lot to see. Of course you can add this one to your collection if you're trying to build Android 4.4 from the apps up, like some kind of software Megazord. The app will replace your default email if you're on an AOSP-based ROM, but probably won't if you've got a manufacturer skin. I haven't had any issues on my daily driver running unrooted Android 4.2. Check the download links below.
File name: EmailGoogle.apk
Update: For Exchange to work, you need to flash Exchange Services as well (thanks, Ray!)
File name: com.google.android.exchange-6.0-893803.apk
Source: Ron Amadeo (Google+)