For the most part, despite a few geographic mashups like twittervision, Twitter users have existed in some amorphous location best known as cyberspace. But a new service, TwitterLocal, threatens to actually drag Twitterers into the real world.

TwitterLocal is simple to understand: you enter a city, state, or postal or zip code, and a radius (1 to 50 miles) and it pulls down the public tweets from everyone in that locale. You can get the results in RSS, on the web, or via a desktop Adobe AIR application. Itll be interesting to see whether this changes the Twitter dynamic at all: would you be more or less likely to participate if you knew your real-world neighbors could be watching?