Brightkite will be awesome once they start using GPS.  Until then, do I really want to manually enter in address information for every post that I make?  Maybe I'm just a crotchety old Dodgeball user but I much preferred their hack for getting around a lack of GPS - adding and @location, and then looking up that location in a central database.  Damn you Google for leaving one of my favorite web services to die on the vine.

By far my favorite mobile social network. Still in beta so not many people use it yet, unfortunately, but it allows you to geolocate your notes and photos (twitter integration will tweet any or all of this info too, including setting your location on twitter accordingly). Rumor has it an iphone app will make it much easier to send locational data.

One of the coolest features is that it tells you when your friends or anyone on the network check in within a certain distance from you. Great tool for meeting up with friends and conferences or if you all live in the same city.

Additionally there is powerful granular control over privacy of your posts if you so choose.