What to do when Open Source Licenses are not Compatible

In releasing the LinuxQuestions.org Wiki I had to choose between multiple free licenses. When it came down to making a decision it was the GFDL (GNU Free Documentation License) vs. the Create Commons by-sa. I ended up choosing the Creative Commons license for two main reasons: I wanted single articles from the wiki to be easily redistributable and the CC license is much more straight forward. This now unfortunately means that many of the great GFDL documents out there cannot be included. The LQ Wiki is aimed at becoming a large free/open resource for the Linux community and the potential duplication of effort caused by this seems like a waste. I am now considering adding the ability to choose a license for documents entered into the LQ Wiki, but this will not only greatly complicate things, but it will also mean that the entire wiki will no longer be distributable under a single license. While it seems the desired end result of both licenses is similar, the fact that they are not at all compatible really does seem like a shame. IANAL though, so is there anything that can be done?