From the Wikimedia Foundation
Whereas the Board seeks to respond responsibly to longstanding community concerns about issues of compatibility between the GNU Free Documentation License and the Creative Commons CC-BY-SA license, as well as to continue longstanding traditions of strong community input and control over major decisions affecting the projects, and
Whereas a long period of discussion and negotiation between and amongst the Free Software Foundation, Creative Commons, the Wikimedia Foundation and others has produced a proposal supported by both the FSF and Creative Commons to modify the Free Documentation License in such a fashion as to allow the possibility for the Wikimedia Foundation to migrate the projects to CC-BY-SA, and
Whereas, Creative Commons and the Free Software Foundation (FSF) would like formal support for this license change,
It is hereby resolved that:
The Foundation requests that the GNU Free Documentation License be modified in the fashion proposed by the FSF to allow migration by mass collaborative projects to the Creative Commons CC-BY-SA license;
Upon the announcement of that relicensing, the Foundation will initiate a process of community discussion and voting before making a final decision on relicensing.
5 approval (Jimmy, Florence, Jan-bart, Erik, Frieda), 1 missing vote (Kat)
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The Free Software Foundation (FSF) has announced a new version of the GNU Free Documentation License (GFDL) which paves the way for the Wikimedia Foundation's (WMF) projects, including the popular Wikipedia, to switch to the Creative Commons Attribution-Share Alike (CC-BY-SA) license. 
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The move was announced following discussions between the Wikimedia Foundation and the FSF.

Erik Möller, deputy director of the WMF, explained the reasoning behind this move. "The underlying motivation of this change is that CC-BY-SA is an easier-to-use license granting the same essential freedoms as the GFDL," he stated on the official Wikimedia blog. "It is also more widely used by other educational projects, and switching the license would allow Wikimedia wikis to freely share content with those projects."

Möller also state that "later this month, we will post a re-licensing proposal for all Wikimedia wikis which are currently licensed under the GFDL." 

The change was made in section eleven of the license. It says that conversion to CC-BY-SA is only possible if:
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*The work is licensed under version free of the GFDL
*The work has no “Cover Texts” or “Invariant Sections.” 
*The work must have been added to a wiki, or a similar website, before November 1, 2008.

The condition of the license allows for conversion to the CC license before August 1, 2009, although after that date it will  no longer be possible. 

The Wikimedia Foundation formally decided to ask the FSF for the change in December 2007, with the approval of five of the six members of the Wikimedia board, with one member not voting.

Despite the support of the Wikimedia Foundation, some people have voiced their opposition to the move. On Advogato, Chris Frey sent an open letter to the chair of the FSF, Richard Stallman. "I am writing to express my disappointment with the Free Software Foundation regarding the recent release of the GNU Free Documentation License version 1.3," he stated. "The new version 1.3 adds a new clause, section 11, which, according to the FAQ, allows wiki sites to relicense specific content from GFDL 1.3 to CC-BY-SA 3.0, for content added before November 1, 2008. They have this relicensing option until August 1, 2009. This, in my view, is a serious moral mistake and breach of trust. Even if this new clause does no harm, it is still the wrong thing to do."