I'm in a similar boat, having bought a new MacBook online that still hasn't even arrived yet (purchased mid-August but with supplies low because of the updates it looks like they had to ship mine straight from China, according to FedEx).
It's supposed to arrive tomorrow, just a week before the updates. For me, as a low-end user (using only a MacBook), I don't really care about processor upgrades enough to return it, but if they offer some other great new feature, I probably will.
When I bought my current iBook last year, they released a version three weeks later that had Bluetooth and a larger hard drive, something I've been kicking myself for ever since. So I'm definitely not going to just keep this one if the same thing happens.