I'm quoting the following from Groundchuck of www.rwoguild.com. This was posted on TenTonHammer. I agree with every point in the talent tree as well as the reasons provided. The two points I'd leave up in the air as preference and gear are Imp Bloodrage vs Anticipation.
Arms: 3/3 Imp heroic strike. Heroic strike is a ton of threat, and making it cheaper means I can use it more. (with focused rage it becomes 9rage for HS!)
5/5 Deflection. Parry is the best thing you can do. You get 50% (30%?) haste increase on your next white attack after a parry. It's avoidance and threat combined!
3/3 Imp clap. Thunderclap mitigates a huge amount of damage. There is really no excuse for a tanking build without it. Addidionally it's a huge amount of threat when muli-target-tanking. Accept no substitutes. It stick on raid bosses.
1/1 Anger Management. I haven't had this for a very long time, but I'm liking it. It passivly generates rage while in combat meaning every 17 seconds I get another shield slam, every 9 seconds a heroic strike etc... So far so good. (It was an extra point anyway)
5/5 Cruelty. Crit is threat and crit is fun.
2/2 Improved Bloodrage. This is 16 rage at the start of a pull. It will also cause a tiny bit of threat to a group of mobs which can help to bring them together for Thunderclap. Basicly it lets me start every fight with a shield slam.
3/5 Anticipation This talent is awesome. I have 3 points because I have plenty of defense from gear. If you can't meet 490 def easily put in more points.
5/5 Toughness. Armor is a good thing. Ask a bear.
5/5 Shield Spec Rage from blocking is a good thing. Also opens up Imp Shield block.
1/1 Improved shield block. Lets you block an extra attack. Most important against raid bosses because it means another attack that's not a crushing. Also with Thunder Clap up very few bosses will attack more than twice in 5 seconds. This is how you can push crushing blows off the table. Without this talent you are much more likely to get crushed.
1/1 Last Stand I wouldn't dream of tanking without it.
3/3 Defiance See above.
3/3 Improved Sunder Frees up more rage for shield slam and lets me get up to 5 sunders faster. It's awesome. Stacks with Focused Rage for 9 Rage sunders.
1/1 Concussion Blow It frees up Shield Slam and stuns are good.
2/2 Improved Shield Wall If you need a full five points in Anticipation this is where they come from. When **** hits the fan the extra five seconds is very nice to have though. Gives everyone more time to get things back together.
3/3 Shield Mastery More damage blocked and bigger shield slams. Everybody is happy!
5/5 1h Weapon Spec More damage means more threat. It's that simple. Also increases damage of "Yellow" abilities like Devestate, HS, Shield Slam. It's awesomesauce.
Shield Slam The most threat per second available. It's threat, it's damage and the crits are fun. Use it whenever it's up. No excuses.
3/3 Focused Rage Using less rage means you have more rage available. More rage means more aggro. More aggro means more DPS. More DPS means boss dies faster. Get the picture? Smile
5/5 Vitality Strength is attack power, attack power is agrro. Stam is stam. Aggro + Stam = Happy tank.
Devestate It's handy. Getting better with each patch. Great if you're going to offtank and try and stay high on threat. Use a slow weapon if you're going to OT.