Apple Aperture doesn't process raw, in the traditional sense. OSX natively handles most popular raw image formats. they constantly add new supported raw formats (they added the mk3 about 2 weeks after it was available).
Aperture uses CoreImage to process images in realtime per a set of metadata (used for controlling basic editing such as crop, saturation, contrast, etc.) - leaving the original completely intact. it also stores keyword and other data for searching and organising.
i have been using it since the day it came out and it has greatly streamlined my workflow. ever image i have posted here has been processed in Aperture. these have all been raw, except for scanned film or sports .jpg files.
basically my workflow is like this:
-shoot
-offload from cards into projects and albums
-quickly cull the bad ones (using the minus key)
-batch set white balance tweaks, saturation, and contrast for each different shooting situation
-keyword
-export to print or web
that took maybe 10-15 minutes for the 850 or so pictures i took on saturday
if you are a photoshop user, you can round-trip your images from inside of the program. i only really use photoshop for scanned negatives to remove dust. i'd be suprised if i used it for than 1% of my digital photos.
i went through all 4 Lightroom betas. it works in a fashion very similarly to Aperture, but with some expected Adobe behaviour. because i've been using Aperture since the beginning i'm sticking with it... but i do recommend Lightroom over Aperture to all people who are looking for a solution. it works on both mac and windows.