Nope, its definately part of the resurgence... but it was inspired by the already active Illuminati Theories. Wilson and Shea were Playboy Magazine Editors and had to deal with all of the crazy letters to the editor. Illuminatus was conceived with Bob asked Bob "Wouldn't it be funny if ALL of these conspiracies were true?"
As for the Dan Brown stuff... he was more likely inspired by Holy Blood, Holy Grail which also inspired RAW's Historical Illuminatus Chronicles.
If anything Illuminatus! took advantage if the meme and probably popularized it. Just like RAW popularized 23 Enigma and the 8 Circuit model, neither of which were his creation... but he could explain them a hell of a lot better than the people that did come up with them
