Wikitravel:Why Wikitravel isn't GFDL
A lightweight alternative
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 (by-sa) 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, author attribution, 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.
Creative Commons has plans to issue a new revision of their suite of licenses at some point in the future. Compatibility with other Free licenses is "a top priority", and we can expect that some time after that version change, articles created on Wikitravel can be distributed under the GFDL. (GFDL compatibility was supposed to be part of the 2.0 version change, but didn't make it in.)
If and when the CC licenses become GFDL compatible, other Free Content authors can include Wikitravel content into their work, even though we can't include GFDL work into Wikitravel.