First, it was Dodgeball — the first supposed local social network. That got bought by Google and dumped into the trash can. Then it was Twitter. It’s evolved so much more that “what are you doing?” has lost its value. Recently, Yahoo! launched its own play FireEagle in private beta (we covered it here) which is starting the location-craze again — with plans to have multiple input/output methods looming across the web and devices. But that’s not so much of a location-based social network as it is a “where are you, exactly?” version of Twitter. Here’s one that is — BrightKite.
Currently in a private beta also (first three comments get an invite!), the service is based around locations and what you and other people — your friends, the world, etc. — are doing at what places. After signing up, users can search for their location in the places box and “check in” — similar to Fire Eagle, 
a Facebook status or a Twitter message. After checking into that place, friends are updated, and you can see who is within your proximity or where your friends are at the moment in the same fashion.
Once the user is checked into a place, there are a number of actions that can be taken. On that place itself, a 140-character Twitter-like note (i.e. we went to Alcatraz today!) or a photo can be posted, and recorded in almost the form of a travel diary — except that it’s ongoing. An additional step that you can take is opt into their mobile service and “placemark” your current place — useful if it’s a specific location. So, for example, where you’re at work, you can check in by texting “@work” to 80289. This gives identity to places and lets you easily let your friends know where you are.
Apart from travellers, whom it’s obviously extremely useful for, I think a huge potential market is urban hipsters. With Twitter being turned into a more of a “broadcasting” mechanism than meeting up and seeing what your real friends are upto, not to mention the vast amount of noise and busyness that fills the streams, BrightKite has the potential to be an invaluable tool.
