What is the Shadowpriest Rotation for level 81 and above?

According to Shadowpriest, it's as follows -

MAIN Shadowfiend, SWP, if (SWP duration < 2s) MF, if (VT duration < 2s) VT, if (DP duration < 2s) DP, SWD, MB, if (evangelism < 5 or shadow orbs < 3) MF, MS

CD if (evangelism = 5) archangel, if (mana < 10% and !DA) dispersion

Open with: Shadowfiend, 2x MF(for Evangelism), VT(For Replen), MB(if you have at least one orb), SW:P, DP, SW:D

Main Rotation: Shadowfiend, SW:P(though that should be kept up with MF casts), VT, DP, Archangel, MB(with at least 1 orb, unless it has been 15 sec, then even with no orbs for Replen), SW:D, MF

Only cast Archangel after all of your dots are up, since it consumes Evangelism you will put up lesser dots otherwise.

I haven't even cast MS yet. I am boycotting it because I see no reason to cast a spell that removes all of my dots.

From Newnoise's Shadow Priest Guide, posted in an MMO-Champion News Post just 8 hours ago.

Opener: Shadow Word: Pain > Devouring Plague > Vampiric Touch > Mind Blast 1-3 Orbs > Mind Flay until first Orb*

Target Health > 25%: Vampiric Touch > Devouring Plague > Shadow Word: Pain > Mind Blast 1-3 Orbs > Mind Flay

Target Health < 25%: Vampiric Touch > Devouring Plague> Shadow Word: Pain > Shadow Word: Death > Mind Blast 1-3 Orbs> Mind Flay

Information regarding rotation (further information can be found on the guide itself) -

Opener - The casting of Shadow Word: Pain and Devouring Plague is to allow you to use your Global Cool Down (GCD) spells to run into position on the pull. This also increases the chances of you having a Shadow Orb stack sooner, allowing for an earlier gaining of Empowered Shadows. Vampiric Touch should then be cast ASAP as our highest DPET spell should remain your top priority. Following this, you want to hope you have gained a Shadow Orb after Vampiric Touch to cast a 1-3 Orb Mind Blast. If you are still without an Orb at this point, continue to Mind Flay away until your first Shadow Orb proc.

DOTs - In all cases, DOTs should always have priority over other spells for their superior DPET. It should also be noted that DOTs no longer clip in Cataclysm so the early reapplication of dots is now encouraged as a DPS gain in some cases. The ideal time to recast your dots is between the second last and last tick of a DOT to gain 100% up time on your dots while also not wasting any cast time or lost GCDs. If Empowered Shadows has fallen off, then a 1-3 Orb Mind Blast moves to the top of the priority list to reapply Empowered Shadows. This opener assumes you need to run in on the pull. Should you find yourself in the position you want to be in before the boss is pulled, then move Vampiric Touch to your first cast.

Mind Blast - If all DOTs are rolling, it is advised that you use Mind Blast on cool down as long as you have 1 to 3 Shadow Orbs. Never cast Mind Blast with 0 Orbs. Also, there is evidence to show that waiting for 3 Shadow Orbs to cast Mind Blast leads to a loss of DPS. To further support this, it is important for Empowered Shadows to have a 100% up time.

Credit for this information goes to Newnoise and MMO-Champion.