Vene's Quick and Dirty Pre-Naxx Prot DPS Guide
This guide is focused specifically on dpsing when not tanking in a raid setting as a Protection speced Warrior.
I. Gear to reach Caps
262 hit (8%)
164 expertise (5% + 1.5% from 3/3 Vitality)
66 hit: Boots of the Neverending Path - Item - World of Warcraft (boots) - Exalted Argent Crusade
60 hit: Spiked Titansteel Helm - Item - World of Warcraft (helm) - Blacksmithing
55 hit: Sphere of Red Dragon's Blood - Item - World of Warcraft (trinket) - Last Boss, Heroic Nexus
61 +16 hit: Engraved Chestplate of Eck - Item - World of Warcraft (chest) - Optional Boss, Eck from Heroic Gundrak
= 258 Hit Rating
31 exp: Shroud of Reverberation - Item - World of Warcraft (cloak) - 2nd Boss, Heroic Halls of Lightning
29 exp: Titansteel Bonecrusher - Item - World of Warcraft (weapon) - Blacksmithing
33 exp: Hemorrhaging Circle - Item - World of Warcraft (ring) - Last Boss, Heroic Gundrak
43 +4 exp: Sharp-Barbed Leather Belt - Item - World of Warcraft (belt) - Last Boss, Heroic Utgarde Keep
= 140 Expertise Rating
Which leaves 4 Hit Rating and 24 Expertise to acquire from any other gem slots. (or enchants if you must) Once you've reached the caps, you'll want to go all out on Strength. As your gear progresses, you'll want to make sure to maintain these caps and when you replace your weapon be sure to choose a slow weapon as it'll improve your Devastate damage.
Low Latency: Shield Slam > Devastate > Devastate > X
High Latency: Shield Slam > Devastate > X
X = Buffs > Concussion Blow > Shockwave > Rend* > Devastate
Heroic Strike should be used if you get too much rage, but since you're only using a 1 hander to generate auto-attack rage... this isn't going to happen too often. I don't include Whirlwind in the rotation as the nearly double rage cost (22 vs 12) makes it more valuable to Devastate instead given that we'll be dealing with limited rage and Devastate can proc a free Shield Slam. Furthermore, since Rend is superior and not usable in Berserker Stance we'll be opting to DPS in Battle Stance.
You can expect to have to keep up one or all of Battle/Commanding Shout, Thunder Clap and Demoralizing Shout. (Labeled "Buffs" in the X part of the rotation) The beauty of the rotation listed is that you'll already be in Battle Stance to apply Rend so if you do have to keep up Thunder Clap, you won't have to worry about stance dancing back and forth to Berserker Stance. Any of these buffs should be at the top of your X priority chain in your rotation when they need to be applied/renewed.
* You can easily move 2 points from Improve Charge to Improved Rend in the Impale spec in order to cater to this and not hamper your tanking at all as Charge's rage gain basically never plays a factor in raid MTing. Even if you don't spec into Improve Rend, it's still worth applying Rend.
Helm: Arcanum of Torment - Item - World of Warcraft
Bracers: Enchant Bracers - Greater Assault - Spell - World of Warcraft
Gloves: Enchant Gloves - Crusher - Spell - World of Warcraft
Boots: Enchant Boots - Greater Assault - Spell - World of Warcraft
Cloak: Enchant Cloak - Major Agility - Spell - World of Warcraft
Chest: Enchant Chest - Powerful Stats - Spell - World of Warcraft
Legs: Icescale Leg Armor - Item - World of Warcraft
Shoulders: Greater Inscription of the Axe - Item - World of Warcraft
Weapon: Enchant Weapon - Superior Potency - Spell - World of Warcraft
15/5/51 - Impale
15/5/51 - Impale with Imp Rend
Those are the Impale specs that I mention throughout the guide. If you aren't planning on using one then just gem for haste instead of crit since you'll gain no benefit from critting really at all and haste will improve your rage generation making for a smoother rotation.
VI. Additional Notes and Credit
This is not a guide for Fury/Arms DPS in any way. It's not about getting the best Prot-style dps spec either. It's about maximizing your DPS when not tanking utilizing your standard tank spec. You aren't going to beat good Fury/Arms Warriors, but by doing this you should be able to contribute some decent dps when not tanking and maybe even keep up with (or surpass) the lazier/undergeared dpsers in your guild. (on melee friendly fights, you can probably beat some ranged dps too)
Huge credit goes to Corbusier for his Fury Guide as it obviously did a lot of the leg work/number crunching for this guide. Thanks to Kavtor for helping to refine the Rotations portion of the Guide as well.