For raiding, the swords is about tied with fist mainhand (S3, talon from Al'ar, ZA drop) and a sword offhand, with both weapon specs. This is because offhand swordspec procs give mainhand hits, and it's apparently the offhand sword that has the majority of procs. So you get almost full benefit of swordspec, but with an extra 5% crit, at the loss of a bit of poison damage.
Highest-damage rogue in my guild is sticking with mace/sword, for the stuns on various fights, at least until we get Talon of Azshara to drop, which likewise is just below swords or fist/sword for damage but with all those nice stuns on various trash/adds.
For PvP, maces is best, again for all the stuns, though swords for raw damage or Mutilate with specific partners (spriest, who should always be targeted first, leaving few/no positioning issues) can be good too iirc.