The elemental invasion has begun. If you don't know what's going on, there is a great post about the event at: http://ravenholdtmanor.blogspot.com/
You can also find info over at Wowhead and Wowpedia.
Go out and see what is leading up to the world changing.
A Note of Caution, finding the elemental rifts can be a pain, they spawn at random times at one of several points in the various zones. If you destroy a rift in a zone appropriate for your level, you can get a daily quest from the mysterious object that appears when the rift is destroyed, which is turned to an Earthern Ring emissary in one of the capital cities. Also if you destroy a rift of each element, you will get a Feat of Strength.