This is a huge change for Prot! Prot Pallies are fine for general purpose tanking currently, but this is the one area where they were completely left in the dust (and for all intents and purposes in Wrath it is the only area where tank selection matters). Prot paladins will be a viable option for progression tanking now.

The only weakness prot pallies continue to have after this change would be an ability to dish out spiky AoE damage (Like, howling blast, thunder clap, swipe) which helps on multi-mob pick up and AoE tanking with movement. For sustained stationary AoE threat pallies are, and have been fine.

I suppose smaller health pools is still somewhat of an issue, but pallies have very high passive mitigation (15% reduction of all damage from talents, and an additional 6% of magic damage), coupled with a permanent shield wall for anything that would reduce their health below 35% makes this even more impressive.

DKs will still be king, but prot pallies are probably going to be in a better spot than warriors and druids now.