I have written a new guide, focusing on backporting Debian GNU/Linux packages to earlier releases.

Detailed discussion of pbuilder as a tool for backporting Debian packages from Unstable/Sid to the current Debian GNU/Linux Stable release. Building the initial environment, care and feeding of pbuilder, apt sources, building, and debugging are covered.

Update, June 13th. The author of pbuilder, Junichi Uekawa, contacted me to ask if he could include my guide as part of the official Debian GNU/Linux pbuilder package. I was quite pleased to give him my consent.