The Play Store has gone through its fair share of evolutionary changes over the years, transitioning from the Android Market to the Play Store, then just shifting design schemes every so often and adding new bits and pieces of functionality. The latest change sees users now having the ability to zoom in on the screenshots for apps, games and other content in the Play Store, so if you desire to have more detail on a specific photo for an app or game you're interested in, you can now zoom in on that content and take a closer look.
This might seem more arbitrary than useful, and perhaps it is to some degree, but there will undoubtedly be many users who actually enjoy having this feature available to them. Having the ability to zoom at your fingertips does have its merits as you'll be able to see more detail on things. This could be extremely useful for some games which show off screenshots of gameplay but are ridiculously small and harder to see, which seem to pop up more often than you would think. While this is now showing up quite commonly it's worth noting that this isn't the first time it's been available as a small amount of users have had access to it prior to now, but it seems Google has now enabled it on a wide scale and it should be popping up for all users throughout today and over the next couple of days.
If the zoom feature is available to you, simply pinch your fingers outward like you would to zoom in on anything else on Android. Once you're in as far as you can go though, the difference in the way that it works is that the zoom isn't stationary. If you take your fingers off of the screen it resumes its original position. If you've used the zoom on Instagram that was recently added, it works exactly the same way so that should give an idea of what it actually looks like when you use it. Although the zoom snaps back once you let go, the motion and transition is quick so it won't take long to zoom back in again if you prefer to.