Out of curiousity - Which bind on aquire heirloom weapon would be best for a Protection spec Warrior now that Cataclysm is out?
If you're referring to 1-85 Heirlooms, I don't believe they're out yet. So for now, the same one used in Wrath of the Lich King remains as the preferential choice.
Venerable Dal'Rend's Sacred Charge - Probably best for tanking while leveling.
Venerable Mass of McGowan - Narrowly second best, but useful for other classes/specs too
Battleworn Thrash Blade - Great before you get Bastion of Defense. Almost useless afterwards.