My quest for true GNU purity has taken yet another step back.
The FSF has a list of truly free Linux distros, and Slackware doesn't make the cut. The FSF sponsors a Debian-like distro called gNewSense, which is, apparently, pure.
One thing that is cool about it, at first glance, is that the distro maintainers have developed scripts to help one roll one's own distro. This may be useful when trying to get Hurd up and running.
As a side note, I guess I don't really believe all this freedom stuff. Life is too short not to be a little pragmatic, but, I do like a challenge. On that level, this is going to be fun.