The hunter has really got a big burst in this Pandaria extension. Very often, while leveling my hunter, if I went into battleground (what I do pretty often), I was often at the top screen of DPS, even though I might be the lowest level of my team.
In fact, when you look at the damage-done scale at the end of a battleground, almost every time, you will see the first places are taken by hunters.
Now, in PvP, there is no rotation really. Everything is depending on the class you are fighting, the situation and many other things. It is situational. But against mobs, there is actually a rotation you can use which will give you a very high DPS. It goes this way:
First, be sure to have Aspect of the Hawk on. Then you go:
Distraction Shot (So your target attacks your pet, this generally doesn’t work this way in PvP because very few players are that stupid) > Serpent Sting > Beastial Wrath + Kill Command + Traps (Snake or Explosive) > Rapid Fire > Arcane Shot > Kill Shot (if you go that far)
Make sure to use Mend Pet if your pet’s health is getting low.