Peter,
This is possible, I think. I've just done a quick search and there are add-ons to the forum software for photo galleries. However this is a reasonable amount of work so we'll need some genuine interest in this.
Would also be interested in comments of using such galleries as an alternative to the current attachment process. You would still be able to put pics in your posts, but the process would be to upload your pics to the gallery first then put links to them on the post.
I would only like to have one location where the pics are stored so would need to see if having two attachment mechanisms is manageable. Would also need to see if pics already uploaded could be placed in the gallery.
As you see, there are a few considerations so I'm looking for comments from quite a few members before we do anything. And I haven't discussed with Scott yet either