Well the reason you don't want to basically Spam Pulv, especially after a Mangle, is that the Lacerate ticks are going to refresh your Mangle CD. Mangle is now our Shield Slam(Mangle Slam?) and we want to use it as priority.
Thus as far as Ri said in all his testing on the Druid forums, you want to only hit pulverize on the first or second GCD after hitting Mangle. On the 3rd GCD after a Mangle rotation you don't want to hit Pulv because Mangle's CD is up next and you don't want to push back Mangle.
The rotation you want is typically(in an opener) Berserk>FFF>Mangle>Laceratex3>Swipe>Mangle>Pulverize>Laceratex3 and repeat.
Mangle procs basically trump everything else as far as TPS is concerned.
You only do want to pulverize in a laceratex3 scenario, as long as the fight is going to get 3 stacks up.
Taken directly from Ri's new guide on the druid forums.
World of Warcraft - English (NA) Forums -> Ah! Bears! Cataclysm Tanking (v4.0.1)
Single Target -
This Priority list:
Mangle / Berserk Procs
Lacerate x3
Pulverize
Swipe
FFF, Demo Roar
Rotation(in a perfect world with no berserk procs):
1st Mangle Cycle: Mangle > Lac > Lac > Lac
2nd Mangle Cycle: Mangle > Swipe/FFF/Demo > Pulverize > Lac
3rd Mangle Cycle: Mangle > Lac > Lac > Swipe/FFF/Demo
4th Mangle Cycle: Mangle > FFF/Demo/or Lac depending on Debuffs > Pulverize > Lac
(Note: Clipping Lacerate is no longer an issue. You cannot clip dots.)