I read at http://creativecommons.org/weblog/entry/7876 about the agreement to modify the FDL to make it compatible with CC-BY-SA, so that Wikipedia articles can be republished under CC-BY-SA. However, I was confused about two things:

1) I thought that the GFDL was already compatible with CC-BY-SA 3.0, since they both required derivative works to be published under the same license. Is there a specific part where they're incompatible, or is it just a case that there are ambiguities about compatibility, and the FDL will be revised to remove all doubt?

2) More confusingly, I don't see how you can just "update" a license and retroactively apply it to all existing content that had been published under an existing license. All the contributors to Wikipedia, for example, agreed to the terms of the old FDL when they submitted their work. How can the updated FDL be said to apply to that work if the authors didn't agree to it?

I'm writing an article about Google Knol for Slashdot, about how they currently allow only CC-BY and CC-NC-BY license options, and arguing that they should allow CC-BY-SA as an option as well, allowing people to copy content from Wikipedia to Knol. I argued before when Knol was first announced: http://slashdot.org/articles/08/02/15/177258.shtml that it would be a good idea to have what would essentially be a fork of Wikipedia where articles could be locked against editing and signed off on by credentialed experts.

-Bennett

bennett@peacefire.org http://www.peacefire.org (425) 497 9002