Er, 64-bit has been around since PPC days, OS X 10.4 etc.
In fact, I read somewhere that Apple has limited machines to 32-bit by default due to a toggle somewhere in the EFI.
Edit: Ok, ya apparently it's just the kernel. Hmmm you could argue Windows is better because at least they offer a completely 64-bit consumer OS. You could also argue that the OS X way is better because it's more flexible (32-bit or 64-bit). Bah.
From what I can tell all Snow Leopard really does is...