CM Crygil has posted a very general thread over on the forums asking players what they think of the various class roles out there: "Ranged/Melee/DPS, Tanking and Healing." As you probably have noticed, those three roles make up what are often called the Holy Trinity in role-playing games and MMOs: either you do damage, prevent damage, or recover from damage, and those three roles make up the basics of most roleplaying combat systems, including the battles in World of Warcraft.
But as quite a few people in the thread say, they're not quite sure just why Crygil is asking for this information. Sure, there are lots of good and informative answers in here (most people actually spread out "the trinity" to four roles, splitting melee/close combat and ranged/magic combat into two parts), but as there has always been, there's really nothing outside of the kind of thinking that's been done before on the subject -- anytime developers try to break out a new part of the trinity of roles, they either fall right back into the stereotypes (a bard that casts magic damage "songs" is really just a dressed up Mage), or they end up breaking the game (mind control/crowd controller is a new class idea that's been played around with before, but as Blizzard has discovered, it's extremely hard to balance that exactly right).
As Crygil later says, these questions are his, not Blizzard's -- he just wants to get some perspective on what the forums dwellers think of how the current roles work. And he promises that CC is "on its way back," so maybe Blizzard will try to do some more experimenting with the different types of roles classes can play.