Cartomapic‘s Mappr is an iPhone and web app which lets you publish check-ins to a specific Facebook Group you’re a member of. One of the first apps to integrate the Groups API, it allows users to select which subset of friends to share their location with on a check-in by check-in basis. The Mappr check-ins are not actual Places check-ins, but you can syndicate them to Foursquare and Twitter.

Mappr is useful if you don’t want to share your location with all your Facebook friends, either for privacy reasons, or because you don’t want clutter the feeds of some friends with irrelevant content. Users could share their check-in to a bar with their bar-hopping Group, or their attendance to a conference with their company’s Group. Posting one’s location to a Group can be a good way to stimulate meet-ups, as the post will send notifications to other members, unlike a Places check-in.

Once users select a location to check in to they are able to choose whether to publish to all their Facebook friends, or select a single Group they’re a member of. If published to a Group, the check-in will only appear there (and on Mappr if it’s an open Group), not on the user’s Facebook profile.

Users can search for Mappr groups and open Facebook Groups to view the check-ins of, or filter their map to only show check-ins by a specific Group.

Mappr’s privacy settings mirror those of Facebook’s, which dictate that only open Group content is public. Therefore, non-members won’t be able to see whether a closed or secret Group has had members check-in to a location, or discover secret Groups within Mappr search.

Cartomapic founder and former member of the Google Maps partnership team Bart Denny says that as soon as Facebook makes the Places API available to all developers, Mappr will be able to publish true Places check-ins, like Loopt does, and use the Places database to populate the app’s database of locations. Currently, Groups cannot be set as a distribution parameter for Facebook Places check-ins, so it’s not clear how the Groups and Places APIs would interact.

A user’s location is often only relevant to friends who are nearby and would consider also visiting that spot. However, many users currently share their location through Places or other apps with their entire network. Mappr solves this issue, so if you’re tired of friends on the other side of the world telling you they’re at locations you don’t care about, consider recommending this app to them.