@feryk, that's perfectly possible with the current zenphoto. You could make a theme where each albums' images are displayed side-by-side without space between, it's quite easy actually. And all you'd have to do is add images to the folder/album to build it up.
I'd like to see more than "thumbnail" and "photo" as rendering hooks. Specifically, I wish to author a plugin to display thumbnails that have been filtered (in my case, desaturated to grayscale) but use a hover/rollover effect to display the unfiltered thumbnail. For that I'd need to invoke URLs that indicate "thumbnail" and "highlight thumbnail" and have event hooks for both.
For future additions like RSS feeds, I'd think having hooks from adding/editing/deleting an album/image/comment may be a good way to architect it -- then the RSS component could be a plugin itself, and just update the feed on those events.