I would really, really like to see users be able to post photos in replies to photo gallery posts. Often those replying want to apply different photo-paint techniques to the originally posted image and then share it within the reply, or post an image of their own for comparison to the originally posted photo.
It would be ideal to be able to use image/file manager to attach photos within the replies, but at the very least I'd like to be able to link in photos with image tags.