Privately run WoW servers have been dropping like flies in the last day or so after receiving letters from Blizzard's lawyers under the DMCA. They've been shut down so quickly and rapidly that it's being heralded as "the end of private servers" by quite a few people. The biggest and most well known servers such as Toxic WoW and Ani-WoW are more or less all gone already, and it seems that it's only a matter of time before the smaller ones go down as well. Supposedly, this letter has a pretty long list of sites and servers that are to be taken down.
Some of these sites have just called it a day, shut down their servers and will move on with their lives, but a few others are already talking about starting them back up elsewhere, 'underground.' It's the internet, and at this point, that just seems silly. Blizzard is watching, and it seems this issue has moved up a notch on their priority list. My advice? Don't tempt fate.