Deathwing has changed the face of World of Warcraft and in Cataclysm players will experience first hand his destruction, being forced to take on new challenging content as well as having their familiar homes and memorized landscapes forever changed, needless to say leveling in Cataclysm will be new to every single WoW player.
The question stands though, what is the quickest way to level 85? Depending on your class and specialization this answer can vary.
What will not vary is the "BEST" method, the quickest method.
While healers and tanks might have a slight edge in the dungeon leveling segments of Cataclysm with instant ques, we can say that based on previous expansions as well as time tested experience that leveling in the quickest way possible to 85, be it from level 1 or level 80, will require a large focus on questing.
While it will be possible to level via grinding and battlegrounds in Cataclysm neither of these methods provides near the experience questing will provide.
In addition to the experience questing will also provide much needed gear upgrades and gold, battlegrounds do not do this nor does grinding.
The fastest way possible to level 85 will take you down all new roads, and as with any new road traveled it's always helpful to have a roadmap.
The best roadmaps available come in the form of Cataclysm leveling guides and the best of the best Cataclysm leveling guides are Zygors Leveling Guide and Dugis Leveling guide.
Both these wow guides are time tested and backed by the best names in the Warcraft leveling guide industry and as with previous expansions they both providing extremely fast and extremely reliable in game Cataclysm quest information.
What makes both Zygor and Dugis unique are their quest paths.
Quest paths provide not only the quest you should complete to level the quickest; they also provide the best order in which to do them, a road map of your journey across the new world.
Leveling to 85 in Cataclysm isa brand new experience for everyone, the difference between the people who reach level 85 in a day or two and those who reach level 85 in a week or two will be their access to a road map, in this case access to the right Cataclysm leveling guide.