I did the math last week, and rogue is by far the most underrepresented.
(src) i can't post any links on mmo yet, but just look at the wow rogue forums, topic id# 20752408713
Of everyone above 2k, these are the percentage breakdowns for those projected to get gladiator (as of last week)
rog 15.10%
dh 17.72%
war 17.91%
monk 19.62%
mage 22.90%
dk 23.46%
priest 23.48%
sham 24.77%
lock 26.46%
pal 26.51%
druid 28.41%
hunt 31.33%
Total 23.71%
I haven't had the time to do the math again as of this week, but it managed to get even worse
As of today there are about 15 Rogues in the US projected to get gladiator. Less than 2% of gladiators will be rogues. About 10-11% of gladiators will be frost DKs. That's comparing an entire class to a single spec of a class.