Matthew, sounds cool, what exactly would that entail from my perspective?
For minimal impact at your end one could do it without any server side code. i.e. just have a remote app that gets the RSS feed for this thread, parses out the pictures, author data etc. and generates some static HTML with only some minimal client side javascript and nothing server-side. You could possibly add some static links in the vBulletin config, so that "PAW Gallery" appears in the quick links section, say. And likewise the PAW Gallery could include "Comment on this picture" type links that link back to the PAW Discussion thread.
To host it on this domain would just need an ftp location and user name / password where the HTML can be uploaded. Obviously this would be a sub-directory and the user id would only have write access to that bit. Or it could even be hosted by someone else and done entirely without any effort / risk on your part.
I believe young people would refer to this as a "mash up" and it's like, you know, veh web two point zero dude.
"though by saying that I'd insist anything we proposed did run on this server rather than externally"
If you run code on your server it's a whole different kettle of fish with proper security implications. You would need to do that properly and it would quickly escalate to more work than it's worth I think. You would also need a LINUX / php type person to do the work which means either hanging out at Rochdale Polytechnic, joining a Counter Strike clan or asking Vuk
There might well be ways to do this via external sites with more approriate web based technologies; I could write something to do it from my home server and on the small scale we have here it would work fine but really that's the "wrong" way to do it and it should be done via something more appropritate for the Internet (e.g. someone like Vuk writes something running on his server that generates the appropriate HTML and PFM just links back to that).
"as I not comfortable with a situation where one user had the ability to remove or impact large aspects of this site's photo content."
The thread is still there. It's just re-packaged into some HTML to allow a more photo friendly alternative view so I'm not sure that should really be too concerning. Also PAW / Theme could continue as is with inline discussion since the external HTML provides a noise free picture view.
Note also that pfm (or whoever) would not re-host the pictures and would simply wrap the supplied links in HTML. This is important, not least as the photos are owned by their respective authors and pfm or anyone else should not rehost without their permission.