Just a day after introducing the new geotagging feature, the Flickr team has released the Flickr Geo API.
It’s simple but powerfull: just add parameters like bbox or accuracy to the flickr.photos.search method and filter any search by location. See the Flickr API documentation for a detailed description of this and other new additions.
Btw, Steward Butterfield has a few quite impressing numbers in his last post about the successful launch of the new Flickr feature…
Update
Flickr can read automatically the EXIF location information of your photos, but you have to enable this feature first. Do it here!