we were working with hg for a long time and had a very elaborate workflow with queues. When we finally switched to git we missed our patch queues a lot. fast forward today, I don't even remember exactly why did we need them as much :).

Today we do all the same only better with git.

If I had to draw parallels I'd say hg's queues are used in a workflow like topic branches are used in git. its a way to 'edit history' that is basic in git but requires patch queue in hg (and don't really comes close in terms of functionality and easy of use). and just like in hg you can't change once you commit your patch, in git you can't (or rather shouldn't :) change once you merge into shared branch.