Google iterates a lot on the Play Store - thenew shade of green, darker and richer than the previous one - is currently rolling out globally, along with the big uninstall button and tweaked list view for apps . We've now had wind of another test, using big cards for apps that can be horizontally swiped through in search results.
When searching for an app, tapping a result will take you to this new view, where you see the current content but instead of in fullscreen, it is contained in a card. Scrolling down makes the card bigger - so the view is as it is now - and scrolling up puts it back in a card. Swiping horizontally, left or right, shows the other results of the search.
It's not clear if this is a test or if it's slowly rolling out via a server-side switch. We know Google tests a large amount of things, most of which go unnoticed; this may simply be one of them - after all, the company has just tweaked the search results layout a few weeks ago, with a bigger first result and more prominent install button. Either way, if we hear anything else, we'll let you know.