I use multi-materials, cameras and environments a lot, but I often create them in an order that I'd later like to change. There's currently no way to reorder them within their respective lists other than duplicating/deleting until you have the right order, and that makes for a really messy file.
+1 I'd like to have this option as well. I've had 2 package design scenes this past year that have gone into a number of extra iterations. My camera and environment lists keep growing and I'd like the ability to reorganize them.
By accident we found a workaround to reorder instances of a multi material (submaterial). You can select/activate any submaterial and hit the del key followed by undo (Ctrl+Z). The deleted submaterial is relocated on the bottom of the submaterial list. (checked in KS 9 and 10)
But that doesn't work for environments or cameras.
+1 for this!
I'd also love to be able to group cameras, environments, and Studios. Either in folders or groups like model sets.