I'm actually beginning something like this myself. The goal is something flexible enough to be a doc man *or* a knowledgebase. My company wants some extras like content rating (similar to reputation) and other things that make it useful in a phone support capacity.

Essentially I was going to borrow heavily from the concepts, schema, and eventually some of the appearance of phplinks and rewrite it in Perl using Class::DBI. I stumbled upon a commercial app, Lore, which is almost a mirror image of what I envisioned anyway (except for being php/mysql-bound).

I started writing my own anyway, but I'm only a few hours into it. Tough for me to find that kind of time. I'm building it in a fashion similar to the RTAPI with which I've become extremely familiar. So if anyone might like to participate, let me know, I'll put it on sourceforge or something.