My thoughts on talents for prot warriors. This is for dedicated prot warriors (have shield slam), not dps/prot hybrid builds.
Essential Talenents: (There is no valid reason to not take these talents)
Arms:
5 Deflection
3 Imp Thunderclap
Prot:
5 Anticpation (5 talents in the first row are required to advance, and this is the best of the talents). Were this higher up it would be merely 'strongly recommended'.
5 Toughness (More damage prevention than anticipation, and a massive increase to effective health).
5 Shield Specialization (Required for Imp Shield Block)
1 Imp Shield Block (Required for Boss mob tanking)
1 Last Stand
3 Defiance
1 Concussion Blow
5 1H spec
1 Shield Slam
3 Shield Mastery
3 Focused Rage
WorldofWarcraft.com -> Info -> Classes -> Warrior -> Talent Calculator
(That build is illegal, it is missing 4 low level prot talent prereqs, but its the core talents)
You must add 4 More talents on the first 5 rows of the prot tree, to meet higher level requirements. These should be spent among the following, imo:
Imp Bloodrage (Immediate shield slam on pull)
Imp Sunder Armor (Rage saver, great in low rage situations)
Imp Taunt (Good in 5 mans)
Imp Shield Wall (Good for MTing progression bosses)
or maybe Tactical Mastery, though I find it less useful than these others.
Thats 8 in arms and 37 in prot.
Highly Recommended Talents:
Vitality
Devastate (There would have to be an extremely good reason to not take this, basically, needing a certain 21 pt talent in another tree).
Other Useful Talents:
Cruelty
Imp Heroic Strike (especially recommended for main tanks, not as needed for OTs)
Anger Management (Should be taken if you put at least 2 in Imp Heroic)
Deep Wounds + Impale
Up to 2 in Demoralizing Shout
Marginal Talents (Have use in certain situations):
Imp Defensive Stance
More points in the low level Prot talents listed above in the prereq section.
I do not think Imp Revenge, Imp Disarm, or Imp Shield bash are useful talents for PvE (at least, not more useful that anothe talent could be).
Builds:
5 Man Tank / Raid OT (mostly low rage situations): 8/7/46
WorldofWarcraft.com -> Info -> Classes -> Warrior -> Talent Calculator
Gives you 2 in demo shout for mitigation, 3 in imp sunder which is used a lot in 5 mans, and 2 in imp taunt, also yused a lot in 5 mans.
Foregoes Imp Heroic Strike because its not very useful in 5 mans or when OTing. Your 2 in demo shout also allows you to apply demo shout for the MT in a raid. More than 2 points in Demo shout are not necessary in most situations, since that is enough to reduce a level 73 mob's AP to zero, barring special buffs.
Raid Main Tank: 11-12 Arms/5-7 Fury/43-45 Prot
WorldofWarcraft.com -> Info -> Classes -> Warrior -> Talent Calculator
You may prefer small changes such as moving 1 from Imp heroic over to a 2nd Demo shout or a prot talent, or the Demo shout pt over to another Prot talent. Or moving Imp Shield Wall to Imp Sunder or Imp Taunt.
This build makes use of Imp Heroic Strike, allowing the tank to use the large amount of rage they get from a boss, to heroic strike in over half their autoattacks.
This will be most effective for a tank who stacks effective health, and has only moderate avoidance.
Impale: 17/1/43 or 17/3/41
WorldofWarcraft.com -> Info -> Classes -> Warrior -> Talent Calculator
Or to get 17/3/43, move 2 from Vitality to Cruelty.
The 17/1/43 build is essentially like 12/5/43, except that if you have low buffed crit rating it is worse, and if you have high crit rating (probably over 20%), it is better. The 17/3/41 build is like this but with a bit of stamina from vitality sacrificed for even more crit. (Remember that you must be reaching that 20% or better crit rating in your tank gear, with less ranks in cruelty!
If your crit rate is high enough, and you use heroic strike for the majority of your autoattacks (Main Tank), this becomes superior to Cruelty for threat generation. With a fast weapon, I calculate that Deep Wounds deals about as much damage as 1 pt in Cruelty. With more than half your autoattacks being heroic strikes, about 75-80% of your damage will be from special attacks. At 75% of dmg from specials, and 20% crit rate, 2 points in Impale is as good as 3 in Cruelty.
Generally, you would need a buffed crit rating of over 20% to make this build superior. If you choose to use 3 cruelty and only 3 in vitality, you sacrifice a bit of stamina for more threat.
One further advantage of this build is that when DPSing, in gear with high crit, and a slow weapon, you will do more damage. Also, you will do more damage when you use Recklessness/Execute, such as at the end of the Shade of Aran fight.
This build should generally only be considered by main tanks with many tier pieces (high agi), who always group with a feral druid.