Browsing around the my Windows Vista at home, I saw this "people near me" icon. Reading more about it, it's a new capability of Peer to peer networking built into Windows Vista. It allows you to connect to literally people near you in the airport, in a meeting room, starbucks etc.

More information about this feature can be found at:
http://www.microsoft.com/technet/network/p2p/pnm.mspx

In addition, it comes with a set of APIs - p2p.lib, p2p.dll and header file in p2p.h.