Check out http://getupandrally.com/
“Rally Up is a new kind of social network for your Real Friends – the people that actually should know your location (spouse, family, close friends, etc.)
Rally Up combines private microblogging with location, allowing users to share text, photos and direct message each other.
Rally Up allows you to check in to the places you go. Every time you check in, your real friends are notified.”
Think foursquare with privacy and heaps of OSM