Hardened Shell
Item not yet on beta afaik, which means it's anyone's guess if it'll make it to live by the time MoP drops. I'm guessing they'll be too chicken to have it go live and potentially cause a huge PVE player outcry.
15-min cooldown is a big disappointment for me. If it was 3-5 minutes I'd be interested in coming back to the game. Meh. I guess this whole "world" and "Alliance v. Horde" thing really isn't that much of a priority. Instances are more amenable to business as usual and less prone to player complaints.