Greetings, warlocks. I know that I have generally focused heavily on PvE instead of PvP, but this is more so due to the fact that PvP is a difficult subject to generalize. Strategies are specific to the composition that you run and what you're up against, and they are exceptionally difficult to define in rote patterns. That's the draw that PvP has over PvE -- it's always changing, always different, always unpredictable, at least in the good cases. Yet there is one thing I can say about PvP: Affliction is the spec of choice.
Then again, when are the few times where that hasn't been true? There might be small pockets here and there when demonology or destruction has some meager viability in the PvP world, but they've normally been rather short-lived. Affliction has generally been our default PvP spec, much as mages have relied on frost. No more! I know people are tied of hearing it, but Mists of Pandaria will fix it.