My current team at work was using XPlanner for a while...but we didn't like it too much. We've since gone back to index cards (since the majority of us aren't distributed; for the rest we just let our manager move the cards around).

One thing you might want to look at, though, is webnote. It's Python, not Perl, but it's so cool, who cares? :-) Actually, most of the cool stuff is JavaScript; the server-side stuff seems pretty simple, and if you've got your heart set on Perl, it shouldn't be too hard to port.

Finally, I agree with the other posters that a wiki would be a good choice. And my favorite? The one I wrote, of course - sk - a (very) simple wiki.