The changes to the Play Store we mentioned last month seem to have taken effect. Now when you're checking out apps on an Android tablet, the home page and the tabs for "Top Paid," "Top Free" and the like will only highlight apps designed for use on tablets, at least by default. If you search for a non-optimized app manually, the full listing will use a "designed for phones" tag.
Check out these screenshots. Here's a DROID MAXX browsing the Play Store's home page, and a quick look at one of the featured apps, Cluster.
Now the same view on a Nexus 7 2013. Notice that Cluster is missing. After searching for cluster and manually bringing up the listing, you can see the "designed for phones" tag of shame right under the developer field.
If you'd prefer that the top lists to be unfiltered on your tablet, just select "all apps" from the drop-down menu, like so. Manual search results are not filtered.
This is perhaps the most dramatic step Google has taken to improve the discovery process for tablet apps, going above and beyond some of their more subtle efforts. That being said, this isn't any kind of curated list: "tablet apps" are automatically sorted by Google based on a number of factors, including API support, screen resolution and size support, and tablet screenshots in the app description. So some apps that are merely functional on tablets, as opposed to "tablet-optimized," may slip through the cracks or purposefully avoid the tag.
Developers, if you want to avoid getting the "designed for phones" tag applied to your Play Store page, Google has some tips over at the Android developers blog. For everyone else, the changes should be appearing automatically in the Play Store on your tablet.
Thanks, Anthony Garrett!