Collaborative work on Adobe Bridge.

Depends on what you want to do.

You "could" share a folder with someone else via DropBox but any intent to coordinate working on the images is fraught with danger and grief. If one person is working on a file, and the other person tries to also work on the same file, I do not think the resulting actions would be good. (Bridge was never intended to be used this way.) However, if one person did some correction and then let the other know explicitly that they were done, than that "could" work.

This would also require the users to constantly Purge the folder's cache every time they opened that folder up because the cache would be different every time.

I think this would work but it would be going into unscripted territory. Good luck.