I think having wikipedia in here sounds like a good idea, at least because it seems to me that wikipedia is a very well-known example of free culture. That wikipedia is a part of free culture should be pretty self-apparent from the way it's defined in the article ("social movement[s] that [promote] the freedom to distribute and modify creative works, using the Internet as well as other media"), and from the license used.
 The self-referencing seems ok, as the text says that writing about wikipedia is ok where it's relevant. If wikipedia is an example of online free culture, then it's relevant.
 As for wikipedia not using copyrighted material without permission, I don't see that as any stranger than FLOSS not gobbling up proprietary software. Free culture things are things that let you copy, distribute and modify them. Proprietary things generally don't, and so using them without permission isn't allowed, and therefore you can't include them in free culture things and have the free culture things remain free (or even legal). If you want to use copyrighted pictures and such on wikipedia, it seems to me that is to ask the owner to change the license, or at least follow fair usage guidelines.