Helio has its Buddy Beacon, DodgeBall (owned by Google) uses SMS and Loopt will be free this year for Nextel Boost users of true GPS phones from Motorola ($2.99 a month next year).
Broadcast your location to a group of friends and family and network. This is something that Mologogo has been doing for free since its beginnings.
According to the Chronicle, there is a major difference regarding privacy between Helio and Loopt services:
"Loopt users, who are being tracked at all times, have to turn off the system if they don't want to appear on their friends' maps. Buddy Beacon requires users to update their location every time they want to be seen by their friends."[Update: Boost/Loopt started "Connected with the Dots", a new location-based game. If you live within 50 miles of New York City you can sign up. You will receive invitations with prize information and location. The first Boost/Loopt user to get there if eligible, wins.]
First on VentureBeat.