The Ubuntu Documentation team has for some time been considering a change in their licensing policy, which was previously a dual policy with Creative Commons Attribution ShareAlike and GNU/FDL. This was good for our derivatives, who could release material under either license, but not particularly helpful for us, because we couldn’t incorporate any material in the Ubuntu system documentation which wasn’t public domain.
So the team has recently moved to a single licensing policy. We’ve chosen the Creative Commons Attribution ShareAlike license because we like the license, and it will enable us to use material published under a similar license, such as the material on the Ubuntu Forums, and the Official Ubuntu Book.
I’ve updated the Ubuntu Documentation licensing policy wiki page to explain the new policy.
I also hope that in the next 6 months it will be possible to finally implement the aging wiki licensing spec, so that the community contributed documentation can also be used under the same licensing policy. Stay tuned!