The arms/prot spec got a fairly significant buff to threat generation with the new improved tactical mastery talents. They add an improved threat component to mortal strike and bloodthirst. As long as you get defiance in prot you can tank any 5 man content. It was previously mentioned, but 490 defence is easily attainable via gearing.
With the 42/5/14 spec you can effectively off tank in kara or whatever, all it takes is gear.
If you want to forgo the tanking option, you can go arms dps with a 33/28 spec and use improved slam with a swing timer (again, previously mentioned).
With player skill and appropriate gearing you can probably still tank with this spec. I personally used the 42/5/14 route and was able to tank anything without much difficulty, and pump out pretty sick dps when that was called for. That being said, the 33/28 route is much better for dps.
Anyways, for leveling either fury or arms is fine till 40, at which point you will want to spec for mortal strike. Rebuild your cruelty and go from there. It is not worth another respec just for endless rage, even with the bug fix. With +hit dual wield fury becomes viable, again as was previously mentioned.
Anyways, my two cents from lvling and playing pandacution.
Sean