In the next beta build the minimum level for entering and questing in Mount Hyjal and Vashj’ir will change from level 78 to level 80. All associated creature will have their levels increased to match the new flow.
Additionally, after careful review and consideration we've decided to increase the hit point values of level 80+ Cataclysm creatures. The new hit point values are roughly double their previous values.
Level 80 (OLD)
Level 80 (NEW)
Players will also now need to be level 80 in order to use the Dungeon Finder System for Throne of Tides and Blackrock Caverns.