1.  Ensure that CLOSE_SESSIONS is set to yes in /etc/login.defs, otherwise
your volume will not be unmounted upon logging out.  Debian bug #163635,
maintainer is Karl Ramm <kcr@debian.org>.

2.  I had no luck when using the Debian mount binary to mount an encrypted
loopback filesystem using the keybits option.  I had to build my own
mount binary using the patch at kerneli.org.  Debian bug #163639,
maintainer is LaMont Jones <lamont@debian.org>.

3.  Debian's PAM distribution does not allow session modules to retrieve
a user's password from the PAM subsystem.  This is why pam_mount must be
used as an auth module (in addition to a session module) on all systems.

4.  Debain's login binary releases root privileges to early, resulting
in failed unmounts.  Debian bug #195048, maintainer is Karl Ramm
<kcr@debian.org>.
