Before going after other people's supposed GNU/FDL violations, we should realize that we don't follow the letter of it ourselves either. I found that the following provisions are broken by Wikipedia. Note that the Title Page of Wikipedia is defined in the GNU/FDL. If we consider each page a separate GNU/FDL document, it is the part between the title of the page and its text. If we consider Wikipedia a single document, it is probably above the text "Main Page" on the main page.
It seems that the smallest amount of broken rules comes when we consider Wikipedia as a "Collection of Documents" rather than "Combined Documents" or a single document, but in any case we break:
4B: We do not list the author of the last version plus at least five authors of the old version on the title page. 4E: We do not add a copyright notice each time a new document is created. 4F+addendum: The license notice of Wikipedia is not in the prescribed form, and it is not put on the title page 4I: Our history section is called "<title> Revision history" rather than "History".
And that's just the English version. Other languages have even greater problems. The German version already starts with not containing the GNU/FDL but only a link to it. Some of the minor languages have not even that.
Andre Engels