In comments to the last post, people are saying that the real problem is that there is a tank shortage. I think the tank shortage could be attributed to raiding requiring extra healers as well.
It seems to be a lot harder to find a tank now than it was for the first few months after TBC. The tanking classes are warriors, druids, and paladins. Maybe raiding requiring more healers is pushing would-be paladin/druid tanks to switch to healing specs, thus reducing the total number of tanks out there.
I'm a case in point. I was Protection for all my TBC levelling and a month or two later. Now I'm Holy. +1 healer for raiding, -1 tank for 5-mans. And I think that this may be a fairly common experience for paladins. How common do you think it would be for people to go the opposite route, from healing to tanking?