One of the main important changes is in Section 11 which now enables wikis to be relicensed under the from the earlier GNU Free Document License to the more flexible Creative Commons Attribution-ShareAlike (v3.0) license. The condition is that such relicensing is completed by August 1, 2009.
That means, the Wikipedia community now has the choice to relicense Wikipedia under a Creative Commons license. Check out the FAQ for this change to the license.
It would be hard to overstate the importance of this change to the Free Culture community. A fundamental flaw in the Free Culture Movement to date is that its most important element — Wikipedia — is licensed in a way that makes it incompatible with an enormous range of other content in the Free Culture Movement. One solution to this, of course, would be for everything to move to the FDL. But that license was crafted initially for manuals, and there were a number of technical reasons why it would not work well (and in some cases, at all) for certain important kinds of culture.
This change would now permit interoperability among Free Culture projects, just as the dominance of the GNU GPL enables interoperability among Free Software projects. It thus eliminates an unnecessary and unproductive hinderance to the spread and growth of Free Culture.