The CC-BY-SA means you are free to:
Under the following conditions:
Dear Contributor to the Ubuntu Wiki,
We are contacting you because you have contributed content to the Ubuntu wiki at http://wiki.ubuntu.com.
The license of content of the Ubuntu Wiki has always been publically listed as copyright Canonical Ltd. Working with the Ubuntu Community Council, Canonical has decided to transition the content in the Ubuntu Wiki to the the CC-BY-SA license. This license is a free culture license and is the same license used both by the Ubuntu Documentation wiki  since 2007  and by Wikipedia.
If you are happy with the idea of this transition for the content you have provided, you do not need to do anything. If you have problems or issues, please read the feedback section below and contact us.
The rest of this message provides a rationale, details, and information on providing feedback.
= Decision =
After discussion among the Ubuntu Community Council, it has been decided that the material on the Ubuntu wiki should be licensed under a free license, CC-by-SA. The Ubuntu wiki will be changed to make this clear to those creating or editing pages, and of course external links from the Wiki to material under other licences will continue to be welcome.
This decision is not intended in any way to underestimate the value of contributions, but rather to ensure that the material on the wiki complies with the same standards of openness as the Ubuntu project as a whole.
= Rationale =
The Ubuntu wiki is a collaborative resource, and the product of the Ubuntu community as a whole. Its content, put together by many contributors with different knowledge and points of view, is immensely valuable to us all. Unfortunately, at the moment, there is no clear definition of what rights contributors to the content retain over the material that they post, or the extent to which other persons are entitled to copy or modify the material. For example, it would be very useful to ensure that community contributed content may be shared by many teams without complex licensing issues, ensuring that those working on content can concentrate on producing the best information possible rather than legal negotiations.
Furthermore, consistent with Ubuntu’s philosophy, it is important that material created for use on the Ubuntu wiki be available for other communities outside ours to benefit from. Using an open license on the Ubuntu wiki allows other communities to re-use material which may be useful to them under terms which are widely recognised in the free software community.
= Feedback =
We would again like to make a good-faith attempt to ensure that contributors of existing material are happy with this change. We invite any contributors who have any questions or concerns about this plan to contact us at <email@example.com>. Given that the re-licensing of http://help.ubuntu.com/community was fairly uncontroversial and since the aim to re-license the Ubuntu wiki at some point later has not brought up any objections, we hope that contributors will welcome it.
In the absence of a substantial number of objections, this change will be made to the Ubuntu wiki after approximately one month.
More details can be found here:
Many thanks for your contributions to the Ubuntu Wiki, and we hope that you will continue to help!
= Exceptions =
If you want to license a code snippet on the wiki under another open source license , please specify the relevant license in the snippet itself. In the event that no license is specified, the license applicable to the code snippet would be the same as that applicable to any other material on the wiki.
 See http://creativecommons.org/licenses/by-sa/3.0/