Yesterday, Apple released updates for Mac OS X Mountain Lion 10.8.2 and Aperture 3.4. I downloaded and installed both. Apparently, Apple also released Digital Camera RAW 4.00 along with the updates, though this isn't mentioned anywhere in the release notes.
Of note, Digital Camera RAW 4.00 processes RAW files from the Nikon D800 a bit differently. Aperture tells me that all my old D800 files were processed in an earlier version of Digital Camera RAW and presents me with an option to reprocess the files with the new Digital Camera RAW. If I do so and apply the Apple default settings in the RAW fine tuning brick, I see that the new Apple default is significantly reduced settings for Moire and Edges.
The difference in the new processing is very subtle, though I think I detect a bit more sharpness in my images after reprocessing.