2004: Ubuntu is entirely committed to the principles of open source software development; we encourage people to use open source software, improve it and pass it on.
2006: Ubuntu is entirely committed to the principles of free software development; we encourage people to use free and open source software, improve it and pass it on.
2008: Ubuntu CDs contain only free software applications; we encourage you to use free and open source software, improve it and pass it on.
2010: Ubuntu core applications are all free and open source. We want you to use free and open source software, improve it and pass it on.
-- Fuente: archive.org. Las cursivas son mías.
There are excellent proprietary applications that we would love to make available to Ubuntu users and we work to do that.
-- Matt Asay, Canonical's COO