I recently went to a smugmug meeting where the guest speaker was Art Suwansang discussing the benefits of Lightroom 3. For the record I'm an Aperture user, I only used the beta version of LR and haven't used it since it was released for sale and currently have CS3. I don't think you can really compare CS#(whichever number) and LR since they are for different tasks and doing different things. CS# is pixel manipulation and LR is image manipulation, metadata, organization, editing and more just as Aperture is. LR and Aperture both allow global manipulations that can be applied to groups of images at once. For instance you want to adjust the white balance for shots taken under the same conditions, just one adjustment and you take care of them all. Same goes for metadata.
Some of the things that did impress me about LR3 is the lens profile, you can correct the barrel distortions from any lens that is in their database. You can also correct for linear distortions without the expense of buying a tilt and shift lens. Additionally the new noise distortion was impressive and I liked the graduated filter feature, much easier than making layers and such in CS.
Since I've started using Aperture I rarely go into CS#, I can do most adjustments to exposure, sharpening, spot removal, color manipulation.... Additionally you never actually change the pixels in either LR or Aperture, both programs simply apply the changes you wish to a version of the image, leaving the master image untouched so there can never be an accidental adjustment to the original. It also saves disk space since you are not saving multiple copies of the same image but just coded instructions of what to do so you can many different versions as you work to see what works best.
You can export easily to various entities, facebook, smugmug, flicker and with Aperture it is easy to apply a watermark to every image as it is exported. I have different export profiles saved that designate size, file type and watermark and I just choose the appropriate one for the selected images, done.
If you do need to do something more complicated both programs export directly to CS# and then save that image as a version back in Aperture/LR when you are done.
I can't even imagine trying to edit in CS, right now I upload, run through assigning number(star) ratings, limit my results and go back through till I have the best then start any needed adjustments.
Sorry this got so long but I'm definitely sold on the benefits of Aperture or LR as tools for image management, editing and the majority of adjustments.
Anyone care to compare Aperture and Lightroom?