"Note that right now, Launchpad can only be built and run on Ubuntu (8.04 "Hardy" to 9.04 "Jaunty")," the documentation states. "That's not a design decision, it's just a consequence of the fact that, until now, all its developers have been running Ubuntu."

I've always considered Launchpad to be a strategic play for Ubuntu. It helps them to build their community and it helps to build package availability for Ubuntu. If there was the will, I don't doubt that a tar ball could be created (if not a deb), shouldn't it just be a case of ensuring that package/app dependencies are met?

That said, open sourcing Launchpad is a good thing for Ubuntu and the community.

It means that the community can freely and openly contribute to the development of Launchpad itself. It also means that those that don't necessarily want to host their efforts on Canonical's Launchpad, could host their own Launchpad site. Open source is always about choice and preventing vendor lock-in. With Launchpad now open source, Ubuntu is helping to fulfill the promise of open source for its community and not just talking the talk - but walking the walk as well.