I have created an application called Owlorbit for iOS & Android where you can create map-based chat-rooms and see where certain groups are: http://www.owlorbit.com
We are in beta right now so it's free to use. It'll always be free for consumers but we are eventually going to charge businesses. Users can create common meetup points to have everyone navigate to, search for common POI's, and call or email employees.
It'd be great to know what features people who use fleet-tracking software would need. Thanks!