UPDATE: Relicensing is now possible:
Wikimedia and GFDL 1.3 copyrighteous Mon, 10 Nov 2008
More detail at:
We are very grateful to the Free Software Foundation for working with us to develop this re-licensing language.
The only change is the addition of section 11, "Relicensing". This section permits "massive multi-author collaboration websites" (i.e. wikis and wiki-like websites) to relicense GFDL content to the CC-BY-SA, under two key constraints:
- Newly added externally originating GFDL content cannot be relicensed
after November 1, 2008. (In other words, we should stop importing GFDL content from non-Wikimedia sources, unless they plan to switch as well...)
- The relicensing clause will expire on August 1, 2009.
Relicensing can only be done by the operator of such a website, not by any other party...
- As a heads up, communities should be more careful with importing
external FDL content, unless they know for sure that it will be migrated to CC-BY-SA in the near future.
The Wikimedia Foundation:
will present a proposal for dual-licensing all Wikimedia projects currently using the GFDL, by January 15, 2009. It will be published on the foundation-l mailing list. This proposal will be discussed and revised through open community discussion, leading to an open vote among all active Wikimedia contributors (to be defined using similar criteria as the Board elections). If a majority of community members favor migration to CC-BY-SA, it will be implemented. -- Licensing update/Questions and Answers at Meta.
See also the Creative Commons blog post, Wikipedia licensing Q&A posted, 15 Dec 2008.
Also watch for updates at Licensing update at Meta.
CC-by is one-way-compatible with GFDL - meaning that CC-by content can be used in GFDL work, by not vice-versa.
Source: James Grimmelmann, Associate Professor at New York Law School, (Institute for Information Law and Policy). ([cc-licenses] CC-BY=>CC-BY-SA/GFDL, Apr 19, 2007.)
See also [Wikinews-l] The Wikinews Licensure Poll is closed, Sep 2005.