Pathal at EJ has produced stat weights for rogue PVP in MoP - this is great news as there was a lot of debate and uncertainty about PVP Power and Agility.
Something that's been brought up in comments and discussions with rogues is the value of haste. From a theorycrafting perspective, haste is ranked highly due to the increase in energy regen and white damage it brings. In PVE combat (outside of quirky raid mechanics), haste is great because the restriction on your damage output comes from energy starvation - in PVP, this will not always be the case. Depending on the situation, your energy bar may frequently fill up, and this downtime wastes a lot of the benefit that haste would bring you. How much downtime you have will vary a lot - in arenas, if you're the easy kill and find yourself being tunnelled mercilessly, your energy shouldn't cap too often. Stuns will let your energy regen nicely and fears (should) break from damage before you're back to 100%.
If you find that you're spending more time being kited or controlled, haste is not going to be of much help and mastery will let you do more damage when you eventually connect with your target.
The priority for stats are currently looking like this;
3% Hit > 3% Expertise > PVP Power > Agility > Mastery > Crit > Haste
Burst of Speed
3% Hit > 3% Expertise > PVP Power > Agility > Haste > Mastery > Crit
I've listed two stat priorities depending on your talents. I was initially very disappointed with Burst of Speed - I'm now warming to it a lot and prefer it to Shadowstep vs mage teams. The lack of friendly dispels and the increase in snares seem to make me very vulnerable to defensive peels, much more so than waddling around in S9 with assassination. The energy hit from BoS is pretty severe but haste definitely helps out with regen.
The values are based around BiS gear so the advantage that PVP Power has been shown to have over Agility will not be as apparent in blue gear - if you've already gemmed with full agility gems it's not worth changing them unless you have gold to burn.
Notes for PVP Power and Resilience
PVP Power increases damage done to players and their pets or minions, and increases healing done in PvP zones (unless you're a rogue - recuperate doesn't benefit from increased PVP Power). Adding 265 points of PVP power gives you a 1% increase in damage. In short, PVP Power is a great stat. For a full explanation, take a look at Eldacar's guide to PVP Power & Resilience. It's a ~very~ in depth analysis that's worth reading (or at least skimming through for the graphs).
PVP Resilience decreases the damage you take from players and pets - every player has 40% as standard and there is no hard cap. According to Eldacar's theorycrafting, resilience gives slightly increasing returns. I haven't included Resilience as its value will depend on how much damage you're likely to take. It's way too early to tell, but so far I'm finding that I'm only being tunnelled in BGs. If the comps you are playing makes you the easy kill, then resilience is going to be a lot more valuable than if you're just soaking up AoE.
Using Pathal's values I'll put together a socket calculator to help decide whether it's worth missing out on socket bonuses when gemming.