Yes, you can have a Night Elf mohawk. That's the biggest thing you should take away from the new files uncovered by Andrige, a WoW fan artist. They show some of the new hairstyle options for various races showing up soon in a Barber Shop near you. He sent the files off to our own Big Bear Butt Blogger and to Phaelia of Resto4life. The Male hairstyles can be found at Big Bear Butt, while the female hairstyles can be found at Resto4Life.
Right now, it looks like they've mostly swapped hairstyles between races -- male Gnomes have the Forsaken male hairstyles for example, while Night Elves seem to have taken a page from the Blood Elf book. Still, there are a few seemingly new unique hairstyles, such as the aforementioned Night Elf mohawk and new horn types for Tauren.
of course, most of these new hairstyles aren't even immediately usable in the Beta barbershop yet, either, but it's likely that we'll see them in a future build. Also, I would imagine that we will see more hairstyles (hopefully more new and unique ones, specifically) coming as the Beta continues, but it's nice to get a sneak peak at what we have so far.