AFP, the ban was ordered by federal court in October 2007 but is just now being imposed. Said judge Carlos Alberto Simoes, the titles encouraged "the subversion of public order, were an attack against the democratic state and the law and against public security." (Just so you're clear: EverQuest is an attack on democracy, but censorship isn't.)
Of course, the ban is just on the sale of the two games. Each title is about nine years old, with their latest respective sequels (EverQuest 2 and CS: Source) released in 2004 - not exactly the most timely censorship. By that timeframe, World of Warcraft has about five years left before Brazil drops the banhammer. Let's hope Blizzard can get out Wrath of the Lich King before 2014.
[Via CVG; thanks, Vitor]