Like this? ;-) http://tools.wikimedia.de/~magnus/catfood.php?category=Flags_of_Costa_Rica
I'm new to RSS feed generation, so please text and tell me if there's something broken/odd.
Tech info: This shows the latest 10 images in a category, according to img_timestamp, not cl_timestamp. So, it really does show the latest images uploaded into that category, and not the latest added to that category (though these are often the same!).
Magnus