gnome-background questions

My friend seth is doing something very cool and playing with CC’s new autocurate tools, in pairing with GNOME, to see if he can autoupdate the background.

His critical questions that I’m passing on to p.g.o (he’s only on planet fedora):

  1. is it possible to have the gnome-background-changer run a program to determine the image it should be displaying?
  2. if not what is the best way to have a program run, per user, from time to time?
  3. Has someone else already done this in a more trivial way?
  4. Is the xml format for the image/rotation/transition documented anywhere other than the code?

Leave answers at his post, not mine.

(He didn’t ask me to do it, I think it’d just be cool, as much as I despise the trend to centralize what should be web-wide services in flickr.)