As I've mentioned before I'm a big fan of gear ranking systems that boil down all the stats to one simple number like tank points or kitty points. I like to use the Pawn addon to show my own custom gear ranking right in item tooltips. All the gear rankings are up in the air right now, I can't find anything at all for tanks. But Toskk has a model up for cat DPS 3.0 mechanics at level 70. I took a quick look at it and came up with this set of rankings:
+1 Str = +2.33 AP
+1 Agi = +2.26 AP
+1 Hit = +1.9 AP (up to cap)
+1 Expertise rating = +1.9 AP
+1 Crit = +1.7 AP
+1 Haste = +1.33 AP
+1 Armor penetration = +2.09 AP
The big change here from pre-3.0 is that agility is weaker, now on par with strength or a bit below. That's no surprise given how hard they nerfed agility. We're back in the strength/agility balance of pre-2.3 days.
Be careful how you use these rankings: they're most valid right now for level 70 characters fighting BC raid bosses. And they assume you took all the cat DPS talents. These rankings should be a rough guide for levelling up in Wrath, but it'll need fine tuning when you get towards level 80.
One added comment from ThinkTank: the uber-powerful 2 piece tier 4 bonus stops working at level 80. Sad to lose it, but also glad I don't have to keep dragging those crappy Malorne rags around.
PS, if you want to import this scale into Pawn here it is:
( Pawn: v1: %26quot;Toskk70%26quot;: ArmorPenetration=2.09,
RedSocket=18.64, FeralAp=1, Strength=2.33, MetaSocket=90,
ExpertiseRating=1.9, Agility=2.26, HasteRating=1.33, BlueSocket=9.32,
YellowSocket=16.92, HitRating=1.9, CritRating=1.7, Ap=1 )