On Mon, 16 Oct 2006 21:35:22 -0400, Gregory Maxwell wrote: [snipping an informative post]
As far as dual licensing, the GFDL and CC-By-SA are not compatible.
This statement is a bit confusing. Yes, the GFDL and the CC-BY-SA seem to be incompatible (meaning you can't simply copy stuff published under one license into a work created under the other license).
However, as you note later on, there is nothing to stop you from licensing the same work at the same time under two, incompatible licenses.
But this is not what I had been talking about in the first place. Dual licensing as it is used as a business model in the software industry combines a copyleft license with a proprietary license. You can get the software under a copyleft license for free, or you can pay for a traditional, proprietary license of the very same source code (allowing proprietary derivative works).
Roger