Here’s why I don’t believe it:

• Snow Leopard is a stupid name, no matter how much sense it might make for the upgrade to be derivative of Leopard (as in, not much, actually)

• I don’t see, at this point in the life of OS X (and the life of Windows Vista, as well), Apple releasing a full upgrade that doesn’t present “sellable” new features

• Leopard doesn’t need all that much optimizing; OS X performance has already steadily improved release after release

• If it’s just an optimization pass over Leopard, and it’s marketed as a subset/variation of Leopard, it would be insane, and insulting, to choose that release as being Intel-only

Yet here’s why I’m not so certain:

• It’s very much like Apple to leak this a week early so that we can prepare ourselves and not be too surprised when it’s announced