Twitter, thrillingly, is adding location information to every tweet, so now you'll be able to avoid twits physically as well as electronically.
The service will be opt-in, and the accuracy of the location information will be dependent on the Twitter client used, so the new API is being shared with client developers before it hits the mainstream of the Twitter web and mobile sites.
The Twitter blog suggests you might like to pick up feeds from a specific locality - say where there's an earthquake happening, or a concert, or just what's happening locally. Certainly one can imagine a protest being coordinated in such a fashion: it's got to be more interesting that most of the minutiae-packed tweets carried by the service.
Picking up some form of location information isn't hard on most mobile platforms - even if GPS isn't available, projects such as OpenCellID provide some form of tracking, and at the very least the current country can be detected. The W3C's Geolocation API is spreading into browsers, so websites will soon be able to get a rough fix on your location - with all the usual caveats about privacy and opt-in requirements, obviously.
Getting the location out of an SMS is a lot more difficult, unless you're a network operator, so this announcement is also indicative of how far Twitter has come from the text-message-forwarding service it started out as. ®