According to Amazon's product page, the Game of the Century version of Saints Row 4 will bundle last year's game with all subsequently released DLC and Season Pass content, including the Enter The Dominatrix and How the Saints Save Christmas mission packs. Also included are a variety of ability upgrades, vehicles, and weapon packs, such as the Stone Age DLC and the GameStop contest-winning Polarizer.
Other recent lifelower discoveries include a Complete Edition of Metro: Last Light and a Dead Island Double Pack, neither of which have been officially announced.
[Update: A Deep Silver representative confirmed the upcoming Game of the Century release with Shacknews, but notes that it's only scheduled for release in Europe at this time. "We hope to have more information on what we will be releasing for the Americas and when soon!" the representative stated.]