It varied by department. I am sure there were better options, but we just used SVN because it (mostly) worked and the folder model / shallow checkouts made it easy to explain to nontechnical people.

Adobe has/had a version control software for their products.

i.e you could check out a version of a Photoshop file, make some changes, commit it back. My understanding was the it was aware of layers/etc, so you could diff changes somehow.

you could probably version-control a lightroom catalog file... it's binary but you can still check in a binary file.

Sidebar: Lightroom catalogs are simply sqlite3 databases with a different file suffix. If you ever have corruption issues with them, you can open them up in sqlite3 and export or repair as you see fit.

iGit