Blizzard typically designs its raid zones in three different sizes: you’ve got the one- or two-boss zones, the half-a-dozen boss zones, and the raids with a dozen or so bosses – give or take.

And then, in this thread, Ghostcrawler says (emphasis mine)

…once we say “tanking niches” players have visions of the DK who parks outside of Icecrown until boss 4, 17 and 31 (yes, IC is that big).

At the risk of sounding like a lolcat, ZOMG. No wonder they introduced raid timer extensions!

To put it pictorially:

That’s one way of making sure Icecrown won’t be cleared before Christmas…

(Edit: I’ve seen a few other wry posts around the traps from GC in the last day, and he may well be joking about this – which is unlike Blizz devs, who don’t usually make joke posts unless it’s very obvious that their tongue is planted firmly in cheek, but even devs are allowed to have some fun.)

Edit #2: My guildie Phyl (of Hunters Rhok) has pointed out the official debunking, where GC says

an example on how we don’t want raids to rotate in tanks, I wanted to pick what I hoped was a ridiculous number so that players wouldn’t try and and deduce from my answer how many bosses Icecrown has.

Sadly, my sarcasm doesn’t translate well to the forums. :)

(Unfortunately, if he wanted to convey a sense of “this is just a hypothetical number”, he probably shouldn’t have followed it up with an explicit assurance that he was being serious.)