Ok I've played rogue for a loooooooong time now (like 4 years!) so you can say I know the class fairly well.
These are the "Main" arena specs for anyone that maybe remotely intreseted.
Shadowstep Sub
http://www.worldofwarcraft.com/info/classes/rogue/talents.html?tal=2053001045000000000000000000000000000000000005002431002321210501351
Shadowstep Sub is great - with this spec you will get lots of mobility and High burst damage, however the pre-longed damage really isnt anything to shout about but the burst damage can be really devestating. This spec is all about Mobility, you will always be able to keep up with your target.
To get the best out of this spec you should gem/enchant: Agility/Attack Power
AGILITY being the main stat in this spec .. as you will get 15% more agility from this spec then other specs.
Weapon Wise - Swords, Maces, Fists are all fine for shadowstep. Although I recommened either Swords (for PVE) or Maces (for PVP) for future use!
Deep Mutilate/Sub
http://www.worldofwarcraft.com/info/classes/rogue/talents.html?tal=3053231055521325210510000000000000000000000005002000000000000000000
Deep Mutilate/Sub is an acquired taste, it requires quite alot of skill to pull of but if you can play the spec well the burst and pre-longed damage can be absoloutely amazing. The only problem with this spec is mobility, the mobility sucks but the damage is absoloutely awesome. I've had mutilate crit for around 3k on people with 400+ resilience!
For this spec you really need: Attackpower, agility.
Attackpower being the most important stat for this spec as it relies on high weapon damage from both of the daggers.
Weapon wise you really want a Slow MH and a Fast OH (for posion Shiv) OR you can go for ultimate damage (i prefer - as you can rely on poison procs) with a slow MH and Slow Off-hand - this brings you quite alot more damage but at the same time if you need to shiv it will cost you alot more energy.
Hope this helps!