Aperture and CS2 are, unfortunatly, both a little lacking in the RAW conversion area. Which is sad, since Photoshop has perhaps the nicest workflow management, and Aperture (I'm told, I use a PC is right up there with it).
I've spent a good deal of time in the past month or so evaluating RAW conversion software and discovered that CS2 (Or Adobe Camera RAW, same thing) has an extremely noisy result from RAW. Aperture is even worse according to several of my photography friends.
No clue what alternatives there are for Mac, but I encourage anybody using a PC to check out Pixmantec's RAW Shooter Essentials or BreezeBrowser. Both has very good RAW conversion (I use Breezebrowser for proofing and RAW Shooter for print quality stuff).
Someday I'll start that RAW thread I promised. =)
-Dylan