Yes - where?

I found that an email list was nearly ideal for such work when in the Linux kernel (the famous lkml list.)

This allows threaded discussions, keeping a visible history, and a wide variety of client readers.

Web forums have the history and the threading, but are limited in what they can do compared to
some of the fancier email clients in the hands of an experienced user.

IRC is not threaded, and tends to be more off the cuff conversational.

On a separate topic, I would suggest that a mercurial (hg) interface to the tree, running alongside
the git interface, would be cool.   Aha -- I just noticed http://hg-git.github.com/.  My wish is granted.