Can I make a suggestion? I would love to see a gallery that operates in the same way as the vBulletin albums - so users keep track of their images in their profile, making things easy for them, and easy to remove, edit and add photos at any time. However, the difference would be compulsory pre-defined tag or tags for each image. These tags would be set by the admin. For example, on a car forums, maybe tags like "Porsche", "Ford", "BMW". Then have a gallery index with each Tag displayed as a category. In each category, thumbnails linking to full versions with comments.
This would give tight integration with forum software and has a high chance of being used. I use Photopost with vBulletin at the moment, but users feel that the gallery isn't really part of the main site, and subsequently don't use it as much as they could.
I'm keeping my eye on Xenforo with interest. Once I can migrate my whole site over (currently vBulletin CMS 4.1.x and Photopost), I'll be looking very seriously at this, as I'm loving what I see here.