There has been an interesting discussion taking place over on the EU forums with Blizzard Community Manager Nakatoir about the state of crowd control in PvP. There seems, predictably, to be a focus on arenas in the discussion, which is logical, since they seems to be where crowd control is generally used most effectively.
Nakatoir's contributions are largely in response to complaints from players about chain CC. Chain CC is where an opposing team manage to keep a player controlled for a long period of time by "chaining" together their crowd control abilities. This can be a hugely frustrating experience, as a good CC chain can keep a player out of action for a long period of time. Often, as is the CC-ing team's plan, long enough to land a kill on the CC'd player's team-mate.
Nakatoir provides some great advice for countering CC, rightly saying that chaining together one 33-second chain of CC, as one poster describes, requires a great deal of focus and communication. A CCing team is playing offensively, if they're using the CC to land a kill rather than to turtle, and sometimes attack is the best form of defense.