All of the original information for this gadget is in Japanese, so I can only offer CrunchGear's translation and the better-than-nothing Google Translator. It shoots 200 rubber bands in 10 seconds and takes 10 minutes to load. Apparently in Japan, shooting rubber bands is a competitive sport.
Link (where there's a video)
http://ioanghip.googlepages.com/gattlingrubberband
http://www.youtube.com/watch?v=0GAUnuuBkW4