I am in the process of leveling four UD Rogues, each currently at 49. Here's the Arena strategy that me and my teammate (a Druid) are going to use. I've never seen it attempted before (or even discussed for that matter):

Alright, my Rogues will be specced approximately as such at 70 - http://www.wowhead.com/?talent=fhxfZZEMes0GRcxsu
My Druid (Tauren of course) partner will take a hybrid Resto/Feral spec in Feral arena gear, with HotW, NI, LotP, NS and GoN, the following linked build giving you a general idea - http://www.wowhead.com/?talent=0zZxGhscbRezZAxIz0q

Unlikely specs for PvPs, true, but bear with me a moment...

Now, the Arena will begin with all five of us (that is, all two of us) stealthed. The less plate wearers on their team, the easier this will be. Ideally, as you will see, there's no Paladin on their team to cast BoP, but if there is that's exactly why the Druid was brought along. The Druid will pop out of stealth at 20 yards off and cyclone their Paladin (or their Warrior if there is no Paladin, or Warlock if there neither are present) and run like hell.

This is where I come in. I pop my trinkets, Premed, and Shadowstep behind their Priest (or other clothie if no Priest is present). 3 Ambushes and 1 Garrote (to prevent defensive spells and AoE CCs), followed up by four Imp. Eviscerates (4 CBs per Rogue). After both attacks, I'll still have at least 50+ Energy to burn him down if somehow the Priest lived through 3 maximumly-multiplied Ambushes, 4 Eviscerates, and 1-2 white hits.

The kill should take no more than 2.5 seconds, and I'll immediately vanish after the fact (trinketing or WotF to get out fear if I need to).

In the mean time, their team will have the choice to either group up against a second stealth attack or continue chasing after the Druid. Either one works for me. Assuming they foolishly pursue my Druid partner, I strike their next caster or support (Mage, Warlock, or Druid) without hesitation. My attacks won't be quite as strong as my first barrage, but killing a caster with 4 Rogues shouldn't take more than 6 seconds especially with their Priest eliminated. If they don't chase the Druid, then we just remain in stealth and repeat the first phase again.

Damned if they do and damned if they don't.

I'm very excited about using this strat. Any criticism would be more than welcome. Obviously, we'll take the needed precautions against flares and Perception by keeping patient and equipping a good deal of +stealth gear.