There's been a few epic SR campaigns. Harlequin, Harlequin's Back, Missing Blood, Bug City, Renraku Arcology: Shutdown, Brainscan, and System Failure could all qualify, IMO. In 4th, there hasn't been much in the way of gamechanging campaigns, as they tend to get spread over multiple books now. But Emergence for me is a good example. Suddenly, the whole world goes batshit crazy.