People have been buzzing about Twitter's upcoming geotagging feature for a while, and now the feature is finally here. The function is available through the API only, which means geotagging will not be available through Twitter.com. Although it will be available through Twitter clients like Birdfeed for the iPhone, Seesmic Web for your desktop, and Twidroid for Android phones, which are already supporting the new feature.
If you use one of the clients that supports geotagging, your location will be revealed with your tweets — exciting functionality for reporting breaking news, finding out what's going on near you, or just adding context to tweets from friends. Because it's an API, the functionality is only limited to developers' imaginations, so it'll be exciting to see what they come up with!
One final note (since I'm generally wary of programs that disclose my location), you have to turn on geotagging functionality when using any of these programs, so there's no chance of accidentally disclosing information you don't want anyone to see.