Swarm has had a feature for a long time where you can allow your friends to check you in. It's more than just tagging a friend in a checkin, since it actually creates a full-fledged checkin on the other person's account. It's an interesting feature of Swarm, and not something I've seen elsewhere.
Today I added support for person-tags and mentioning users to OwnYourSwarm. If you tag someone in your Swarm checkin (e.g. tap the + icon and find them in the list), then it will be converted to a person-tag in the h-entry. In addition, any usernames you mention in the text of your checkin will cause the content to be sent to your Micropub endpoint as HTML, including hyperlinks for the names of people mentioned.
Now that I can post checkins on my website, the next step is to automatically copy my checkins from Swarm! I still like the experience of Swarm, and I still get value out of their analysis of my checkins, so I don't see myself leaving Swarm anytime soon. This way, I get the best of both worlds.
Checkins can easily be faked. The Foursquare app does a reasonable job of preventing fake (and accidental fake) checkins, but it's still possible. If checkins weren't posted on Foursquare, but instead were posted on each person's own website, the possibility of fake checkins is much greater. What would it look like to have a way for a venue to know (and republish) checkins that it knows were real?
I've only had Foursquare's new "Swarm" app for a day, but I'm already super impressed. By trimming out all of the search/review features, they're able to focus the app on providing a great checkin experience and providing more ways to connect with your friends.
Make Foursquare API endpoints configurable. It would be great if the API endpoints the app talks to were configurable. Doesn't have to be a screen within the app, but could use the system Settings app to edit the URLs. Ultimately I'd like to point this app at my own server and use it to post checkins to my site.