I mentioned yesterday how I thought some of the world event achievements needed to be tweaked to make them somewhat less reliant on blind luck. I was a little annoyed by the situation and decided to do some more poking around. Despite the vast amount of bad information on the official forums, and the vague information released by Blizzard itself it seems that the hats can only be obtained--now--in level appropriate content. They still drop as world loot off various mobs, but I'm not sure about WotLK mobs. At any rate, I failed to a hat off any low level mob, so I think the loot tables were modified so that it also requires level appropriateness to loot.
With a week left in the event I did not want to give up. Especially considering the hat was the only thing left standing between me and my Wintervale world event completion. Turns out you can two-man the boss in Nexus and I was able to get a friend to run me through on two of my toons. Merrymaker title obtained!