Heres a slightly modified geocodr that returns details about all the clusters that the geocodr finds and the photos that make up the clusters. It can return the bounding box of the clusters too. Options are there to just display the main one, all clusters and/or all points within each cluster. In addition, it can take all the other standard geocodr params.
Example application here: http://geothings.ning.com/geocodrjson.php.
Those with firebug extension can view the json nicely, but it also “stringifies” it onto the page. It returns in both JSON and XML format.