This is quite annoying and when you have a growing number of groups, you do not always keep up with their photocast. Which is a shame as it is great to also follow the life of the group by its photos.
Therefore, I created a little application to generate an opml file that you can import in your newsreader or photocast viewer [1].
Just put your flickr user name in the following form, save the file on disk, and import it in your preferred application:





