Legal guide to GPL compliance

I posted a few weeks ago on a guide to citing Creative Commons works, and just a short while later I saw this not directly related story about a Practical Guide to GPL Compliance, from the Software Freedom Law Center. Where the CC-guide is primarily about citation, and therefore of interest to many Digital Humanists/Classicists who work with these licenses, the GPL-guide is a subtly different animal. Free and Open Source Software licensing is a more fraught area, since in most cases software is re-used (if at all) and embedded in a new product that includes new code as well as the the re-used FOSS parts. In some cases this new software may be sold or licensed for financial gain, or attached to services that are charged for, or otherwise part of a commercial product. It is therefore extemely useful to have this practical guide to issues of legality (including documentation and availability of license information) available to programmers and to companies that make use of FOSS code. One worth bookmarking.