Using a solid block for the shell could avoid seams and screws, and the elimination of human hands in the assembly process would reduce cost and defects. A light, rugged MacBook would certainly be appealing... and might be the perfect laptop to appear in the Iron Man sequel. Apple's industrial designers could pull it off, and certainly the legacy of the all-magnesium NeXT Cube (see Fortune's story about the Cube's manufacturing) hasn't been forgotten by Apple's management team.
Equally interesting is the discussion of where these cored Apples would actually be made. In a Computerworld post also written by Weintraub, he speculates on a MacObserver suggestion that Apple should be investing in a domestic manufacturing plant to use this new process, which would be both a highly controversial move in an economic downturn, and an interesting use of some of the company's $20 billion cash hoard.
If the next MacBook is an all-aluminum model, is that a selling point for you? Let us know in the comments.