The Burning Crusade has been upon us for two months, and already, as I'm sure you've all observed, it has had a dramatic effect on the race/class balance of the game. First off, due to the massive influx of Blood Elves -- they are now the most popular Horde race! -- the Alliance:Horde ratio is more even than ever at 1.3:1 (though of course individual servers do vary substantially). Draenei have not been quite as winning as our love-to-hate-'em elfly friends, placing solidly in the middle of the pack for Alliance races (between Gnomes and Dwarves on the one side and Humans and Night Elves on the other).
How about classes? Well, the stereotype is true: more Blood Elves are Paladins than are any other class (35%). This has made Paladins 6th most popular class for the Horde, which is kind of surprising for a class that just became available recently. Who thought so many Hordies had been secretly longing to bubble-hearth? This having been said, Draenei Shaman are even more popular, relatively speaking, than Blood Elf Paladins -- 49% of Draenei are Shaman. That's a lot of space totems. This also means Draenei represent almost half (48%) of all the Shaman in the game; 39% of Paladins are Blood Elves. Due to the relative unpopularity of Draenei, though, Shaman is still the least popular Alliance class, as it has been for the game's history (not entirely by choice for most of it, of course).
All of this data is from the ever-lovely WarcraftRealms.com census data, and ignores characters below level ten. Head over there if you want more detailed stats of any kind. How is your realm doing?