Thanks for your feedback regarding sets. That's a feature we can certainly add after taking care of the current tasks already in our queue...
Currently, in the mode that includes private photos, we just show photos that are returned by this Flickr API call:
http://www.flickr.com/services/api/flic … dated.html
We shuffle the recent photos in random order, and start cycling through them (shuffling is done because if you have the widget set to stay on for 30 seconds, for example, you probably wouldn't want to see the same 5 photos each time it comes up.
When we add support for sets, how would you like it to work: would you like to be directed to Flickr's site to authenticate (and be able to see private photos), or would you rather keep the customization simple and choose from a list of photosets for a given user without authentication?