About this time last year I set about trying to set up jail's for users coming in over ssh. I had a look at the pam_chroot module. It didn't work due to the change in ssh's architecture which caused ssh to drop root privledges and assume the users before PAM coul chroot. It has since been reworked (or the Gentoo box I was on at the time had a bum module). I spent some time today setting it up. This is how I did it.