Here's a problem I'm trying to get my head around: how can I create simultaneous public and private Mercurial repositories that are continually and automatically in sync without revealing any information from the private repository in the public repository?

Some of my projects, like phpSmug and phpZenfolio contain files I don't want the world to see. These are primarily for automatically building the necessary public files, automatically updating websites, generating documentation and unit testing. Now these files contain passwords and other hacks which the world would love to see, but this is my magic and every magician knows he's only as good as long as the audience doesn't know his secrets.

So how do I create a single directory structure that have files that belong in two repositories, but have only have those changes destined for the public files documented in the public repo?

I've got some ideas. Time for some investigating.