Snapchat just update for me today and they rolled a new feature that I'm assuming incorporates what Zenly did. You can now share your location with friends and see public/shared locations and stories. I can now zoom around the map looking at snap stories of specific locations without waiting for Snapchat to show it to me. It also shows a heatmap over your map so you can see areas with heavy activity. You can't click on the "hot" areas, it's just info.
Interesting, I totally can tap any "hotzone" I want and Snapchat will serve me random videos from that approximate location. It's very interesting to watch sporting events.
Edit: Official Snapchat post: https://www.snap.com/en-US/news/post/introducing-the-snap-ma...