As promised, Launchpad has been fully open sourced (as opposed to the initial idea, nothing has been held back). Get it now, fix your favorite pet bug, and improve tens thousands of people's experience.
Mark Shuttleworth really deserves a lot of praise for this bold and brave move, open sourcing not only the code, but all it's history. It's a fantastic day today.
Update: yes, fully means including soyuz and codehosting, Mark has decided to release everything. The whole history is there.