Google Play today added a "People" section to the Play Store app. Apps and other content that you've hit the +1 button on and have left reviews for will now be visible to friends you have circled in Google+. You don't have to do anything to see this new feature — just open the sidebar in the Google Play Store and it's there, at least for us on version 4.6.17.
Google also gives suggestions for other folks to follow, and other content recommendations that you might like. You'll also get recommendations "From familiar faces," and see who's making the recommendation, so you know who to give a hard time if something suspect shows up.
All in all, it's a nice integration, and should be a good source of discovery for when you're looking for new music, movies and apps.
Thanks to everyone who sent this in!