Dual specs have been one of several hot topics while we watch patch 3.1 progress on the PTRPeople have waffled about whether they mean to spend the 1,000 gold it's going to cost, we've learned that you'll be able to do it anywhere and at level 40, and players of all ten classes are pondering what to use their second spec slot forHowever, according to Ghostcrawler, Blizzard is pretending dual spec does not exist

Maybe I should clarify: with respect to design decisions, they're pretending dual spec does not existRaids and talent trees will be balanced without reference to the fact that some players will be able to easily swap outGC gives some specific examples of things the devs will not be doing, such as "Have a fight that requires 8 tanks, because you know, half the raid can change specs," or "Let Arms be the PvP tree and Fury be the PvE tree, because warriors can just switch out."

This is good news to many, including myselfAlthough if I had been asked to guess, I would probably have predicted they would take this direction, it's good to know that (for instance) raiders won't be effectively required to take spec X and spec Y in order to complete encounter ZDual specs are there to offer us more flexibility, not as another way the devs can make us jump through hoopsAnd I know I'll be taking it on at least a few of my characters.

Sources : Game 2 Play