Taking the last two comments...

-The system is called "Glamours" or "Glamour Prism" there have been somewhat conflicted accounts. But the word glamour is in there somewhere.
-It's coming in Patch 2.2.
-Crafters will make the crystals that will be used to "reflect the appearance of gear" or some such nonsense. They are supposedly easy to make and shouldn't cost an arm and a leg.
-Limitations attached to it so classes cannot hide their true classes, as stated a warrior won't be able to run in wearing a mages robe, and vice versa.