Nethaera has been pretty visible on the forums lately, answering a lot of questions about Wrath of the Lich King. She even popped into one discussion asking about the possibility of being able to change faces in the expansion if only to say that plastic surgery isn't in the cards quite yet. However, Neth mentions that players will be able to change hairstyles, facial hair, and possibly even get tattoos.
So while some of us who've chosen wrinkled, old mugs might not get a rejuvenating facelift (and Undead who don't have jaws will continue to miss them), a lot of customization will be available in the form of new horns for tauren, jewelry, and maybe tattoos. Salthem states the same thing in another thread, saying that there's a lot of development to be done, but that this was the direction they were taking.
The April Fool's prank that Blizzard pulled this year featured the Guitar Hero-inspired Bard class, and pictures of the character had intricate tattoos on both arms. Some early speculation posited that it could be from the new profession Inscription. It could be that the tattoos were just an artist's embellishment for the prank, but it's equally probable that the barber shops in Northrend just might be tattoo parlors, as well.