Exporting from iPhoto to Flickr!
I had seen many commercial solutions that added Flickr export to iPhoto in the past, but this one is the first free one I found. It is only compatible with iPhoto '08. It is similar to the Facebook iPhoto Exporter. Once it is installed, you simply have to select the photos in your library and go to File, Export. The installer adds a new tab called FFXporter. The login is done in a web browser. You can check it out and download it here from MacUpdate.