Wikitravel:Why Wikitravel isn't GFDL
The GFDL is specifically oriented towards software manuals and other textbook-sized references. For Wikitravel, we really want to have each article redistributable on its own. Specific requirements of the GFDL -- such as requiring that all copies of the work be distributed with a copy of the GFDL and a changelog, as well as "transparent" (i.e. source) versions if you distribute over 100 copies -- make that harder.
It's easy to imagine some small "publishers" who might want to have simple photocopied printouts of Wikitravel articles:
For an article of 1-2 printed pages, it just doesn't make sense to require people to pass out another 10 pages of legalese text, as well as floppy disks or CDs full of Wiki markup.
The license we've chosen, the Creative Commons Attribution-ShareAlike 1.0, is much easier and more lightweight. We think that using the Attribution-ShareAlike 1.0 license meets our goal of having copyleft protection on Wikitravel content, without putting an excessive burden on small publishers. All that needs to be included are copyright notices and the URL of the license; this can be done in a short paragraph at the end of the article.
The big downside of not using the GFDL is that GFDL content -- like Wikipedia articles -- cannot be included in Wikitravel articles. This is a restriction of the GFDL -- you're not allowed to change the license for the content, unless you're the original copyright holder. This is kind of a pain for contributors, but we figured it was better to make it easy for users and distributors to comply with our license.