Hey, I just checked out what you meant. Smartor's extention was modified into phpBB Gallery by a dude called nickvergessen and then by stananasov.
Unfortunately the extension is fairly old and the most recent stable version failed to execute properly through my phpBB (some kind of cache error). He is busy with an updated version though.
I was wondering if it was possible to just automatically make 'pages' per image, or maybe embed some of phpBB's code into a page. Is there such thing as using phpBB's topic architecture as a commenting system on other pages?