Well, here are my observations up to this point:
It's obvious that the subject of Wikimedia image permissions is complex and confusing even to members of this group.
I have two groups of websites, a series of political websites with no advertising and a series of "general audience" websites that are educational AND commercial, primarily in their use of ads, especially Google AdSense.
It sounds like I could use images licensed under either Creative License or GNU on my political sites with virtually no fear of being sued. However, it's POSSIBLE that doing so could lead to me forfeiting ownership of material I created. In other words, if I write an article about the relationships between Bill Gates and George W. Bush and illustrate it with photos of both men derived from Creative or GNU, then it's possible that people could begin copying any text I wrote, claiming it is no longer protected by copyright.
If I use such images on my educational/commercial websites, it similarly appears very unlikely that anyone would ever sue me - but the possibility exists. It's further possible that I could lose copyright protection of any text and images I created.
At least, that's what I tentatively infer from the comments regarding the Creative license. Is it fair to say the same applies to images licensed under GNU, or is that a little safer?
Since I can't afford an attorney at the moment, I'm rethinking my use of Wikipedia images. On the other hand, I see people freely using Wikipedia content all over the Internet. Either they never bothered to research the legal issues or they were misinformed. Or perhaps they merely figured the odds of incurring legal costs is too trivial to be concerned with; kind of like downloading music.
I think www.answer.com is an example of a website that makes abundant use of Wikipedia content (at least, text, but images, too, I believe). Of course, they probably have an attorney who has worked out an agreement with Wikipedia.
Thanks again for all the tips.