Blizzard has used its hammer numerous times on many people. Some small, some big... specifically calling to mind Blizzard vs. BNETD. What's unfortunate is that Blizzard is actually winning these arguments and its leaving us with precedence that EULA > The US Constitutions.... If anyone would take the time to read the EULA for World of Warcraft you'll find that some of the claims in it are completely outragous. More or less, if you do something that Blizzard doesn't like, you're liable to have to pay Blizzard for it.
I'm the kind of person who likes to have fun and use my imagination when I play games. I'll agree that I think it can ruin the game experience when players exploit to benefit themselves, but suing them for it just isn't right. It is the fact that not only did I risk getting my account banned but doing things like WoWGlider and writing programs that gave you advantage could also risk major lawsuits that I left WoW in the first place with the ambition of designing my own game where I could have fun with the game world and not have to worry about getting sued. I'm proud to say I made it decently far (though never got close to completion).
Personally, I view Blizzard as more ambitious than the RIAA at pursuing copyright infringements, and most of the infrignements Blizzard pursues aren't infringements at all. A lot of what Blizzard goes after are competitors who make money off Blizzard's product while not reproducing or redistributing their product. I just can't coprehend how Blizzard ever has justification to claim copyrights when a person or team, using their own knowledge and skills, writes their own programs from the ground up to alter the game's performance while not directly modifying any part of the game. In the terms of cheating, its justifiable to ban users breaking the policy, in terms of "3rd party servers" its justification to fix your own holes and make it harder to do.
At this rate, Blizzard's next EULA will say you can't install or play any other video game on the machine that WoW is installed or you'll have to pay three months subscription on the spot.