With the rollout of version 6.7 of the Play Store, Android Police first spotted, Google will now allow you conveniently see if you’re in a beta testing group from within the Store itself, leave and join potential betas, and even give developers some feedback regarding the latest build…
The highlight of the update almost certainly is the introduction of beta testing programs’ support inside the Play Store.
Where you had to manually seek a Google Plus community, join it and then access the Play Store link from your browser previously, now you will only need to go through G+ if the dev requires it, and then do the rest right in the Play Store app.
If you are running a beta, a bar at the top of the Play Store page will appear to remind you. In addition to that, apps that have not yet been openly published but are live only for private beta users will show you that information.
As of now, feedback seems to be a little broken, as it makes look like you are leaving a review, while feedback should instead be private and not visible to anyone but the developer itself. It will likely be fixed as the rollout continues.
You can find the Play Store v6.7 APK here.