You may recall the long running Blizzard vs. MDY battle from various reports here on WoW Insider. In short, Blizzard sued MDY, the makers of the MMOGlider bot (formerly the WOWGlider bot), claiming that the bot violated Blizzard copyright by writing portions of the game to RAM in order to work (since you only have a license to run the game files, and do not actually own them, unauthorized copies are against the EULA).