It's still plenty "mature."
WarCry dug up a post about Age of Conan's North American rating and the details of the game:
It has come to our attention that the North American edition of the game was submitted (by Eidos) to the ESRB without any server-side censorship:
-breasts with nipples
-not full nudity
The ESRB reviewed our application and gave us a rating of Mature 17+. The full rating with descriptors has not yet been publicly announced but will be posted on the ESRB web site on 13 February 2008.
So there you have it. Read more at the Age of Conan forums.