Yes the PC achievements will transfer to the PS3, if for no other reason than this sony mandate:

A Sony representative confirmed for GameSpot that trophy support will be mandatory in all PS3 games submitted for certification beginning next year. "Trophies will be mandatory for titles submitted after January 1, 2009,"
from this article: http://www.gamespot.com/news/ps3-tro...n-2009-6201444

Plus it would be pretty crazy not to implement them if they took the time to do it for the PC anyway. That should be the easiest feature to transfer from one system to the other.