Android 4.4 KitKat should be ready for an official release by the end of this month, but until then the guys at AndroidPolice managed to get their hands on the latest version of Play Store APK version 4.4.21. This is not an official release by Google, as it is still in its testing phase, but the same version or a newer one will be launched when the KitKat OS update is live.
The major change added to Play Store version 4.4.21 is the ‘slide-out’ navigation. The same version will eventually be released by Google, but that might take weeks before it is pushed to your Android device. If you decide not to wait then you can download the APN right now on your phone and install it. It is perfectly safe to flash and your device will work the same.
Also, it seems like Google will push the Newsstand app that should get rid of the Play Magazines. Newsstand should become the default app for reading magazines and news publications.
Download the Google Play Store v4.4.21 APK from here.
Save the file on your Android device, then open it after the download is complete. Confirm the upgrade and then launch the Play Store app to test its new features. There are any major changes added with this release, besides the Newsstand apps and Slide-out Navigation panel. Install it on your device and tell us in comments if you find any other new features.