Positive Technology Journal

mates is a location-based social networking system in the form of a robust web service, or Relationship Engine, and an optional rich media client application, or Relationship Space Navigator.

from the project's website: 

Our objective in creating mates has been to build an open infrastructure to introduce and connect individuals based on the intersection of physical location and other properties they might have in common.

mates is different than the wide range of existing social networking and instant messaging applications. We strive to create an open infrastructure that will allow existing software to harness the power of location based social networking

The current version of mates is geared towards the academic community, focusing on course registration and academic interests. This set of properties could easily be extended to encompass professional or social environments with hooks into LDAP directories or existing social networking applications. and a platform on top of which other new, powerful applications can be developed.