[Chanak]

@Grimar: No arguing with a Protection Warrior being a great tank...doh!, that's what that talent tree is for...but with the release of TBC and more importantly expanded tanking gear, they're not the only ones now who can successfully tank bosses. I know of quite a few guilds who use Tankadins and feral druid tanks on bosses, and they work. The only thing you said I will argue with is "superior." Not really, and here's why:

A Paladin tank has a passive ability called Spiritual Attunement, which regens his mana pool every time he is healed by another player. A Pally tank is actually better at holding aggro as he can increase the threat he puts out from his holy spells via Righteous Fury (and improve that with talents), spam consecrate (holy spell AOE), use Avenger's Shield (ranged holy spell affecting multiple targets), etc, etc to keep aggro focused on him and away from DPSers and healers. He can drop a seal of wisdom on main targets which add mana to any player who attacks that target...and seal of light which can heal fast-attackers like rogues and fury warriors as they attack the target. He can heal himself, he can heal others...all while tanking I might add. With a defense of 490+ a Pally makes a great tank.

EDIT: Forgot to add that Holy Shield keeps the threat going since it damages blocked attackers. Redoubt (+30% to block) + Holy Shield (+30% to block, damages blocked attackers) + Blessing of Sanctuary (damage mitigation, damages blocked attackers) = yet another way for a Pally tank to do what the primary job of a tank is, and that's keep aggro.

Feral druids in Bear put out an excellent amount of threat, have just as much health (and armor) as a warrior, and can heal themselves while tanking via Frenzied Regeneration (superior to Last Stand). Swipe strikes more than 2 targets (superior to Cleave).

Protection Warriors are *not* the only ones able to tank bosses. They also don't offer as much utility as Paladins and Druids do. That utility comes in quite handy. IMO, the idea that Protection Warriors were the only main tanks went out the door with TBC. I'm commenting more on Paladins here since my main is a Pally, and I have the most experience with him. My feral drood is coming along, and I'm getting more experience with her.