At my old company, whenever anyone had a question about the system, we'd reply back with a link to a wiki page with the answer. It worked pretty well. We could either create the wiki page, update it, or refer to an existing one.

This is a good solution. That way, knowledge hoarding is often averted if the creator is willing to add info when it's fresh or lacking a procedure, and finder searches the docs before asking.

I really hate the antique-mindset, amateurish shops where they don't use DVCS, wikis, or configuration management. "Oh yea, only Jim knows how that works" is one signal of intense knowledge hoarding.