Hm, it does work in my reader NetNewsWire. I have found a few things that are different, maybe that's it (Mozilla products are a little more picky it seems...:-). Will be in tonight's nightly.
Hi,
I confirm, I get the same issue using zenphoto version 1.2.3 [3696] (last nightly) with the "withimages" parameter.
My Rss reader is the Sage plugin for firefox.