I've definitely seen searching by lat/lng, e.g. http://search.twitter.com/search.json?q=cant%20wait%20for%20sunday&rpp=100&lang=en&geocode=32.9310417,-80.036498

I've definitely seen searching by lat/lng, e.g. http://search.twitter.com/search.json?q=cant%20wait%20for%20sunday&rpp=100&lang=en&geocode=32.9310417,-80.0364981,50mi http://search.twitter.com/search.json?q=cant%20wait%20for%20... I would guess it's the "by time" filter that makes this unique