vB4.2 is now public Alpha!
and I can now talk about it (I'm on the NDA Alpha test team).
The vBGallery navigation is broken as a result.
I'm going to patch vBgallery for myself (as I've already done for my own add-ons).
I'd be happy to donate the code.
The code will consists of removing the old navigation and replacing it with <navigation> markup in the product file and a small amount of plugin code.
The new Navigation Manger is a big plus in the long term as it makes navigation integration easier for add-on developers.
There is also the new Activity Stream feature.
Ideally new Gallery posts and Comments should flow into this and it has all the hooks needed to do that.
I would recommend a new baseline for PhotoPost vBGallery ... eg. vBGallery v4.0 for vBulletin 4.2+ due to the new Navigation Manager and Activity Stream.