In an exclusive interview in this month's ONM, Zelda director Eiji Aonuma has revealed that there is indeed a definitive Zelda timeline.
Aonuma-san told us: "yes, there is a master timeline but it is a confidential document! The only people to have access to that document are myself, Mr. Miyamoto and the director of the title. We cant share it with anyone else!"
Aonuma-san also told us where Skyward Sword fits into this timeline. "I have already talked to Mr. Miyamoto about this so I am comfortable in releasing this information," he said. "this title [Skyward Sword] takes place before Ocarina of Time.
"If I said that a certain title was 'the first Zelda game', then that means that we cant ever make a title that takes place before that! So for us to add titles to the series, we have to have a way of putting the titles before or after each other."