what's to say that apple arent going to announce/reveal the new product/s and all the details some time then start shipping later so that they don't need to give away details then risk them being leaked...Maybe this new product is too special (if there even is one) to risk. See my post before where i talk about announcements, followed by launches...
But if it is so special and groundbreaking, why announce it in September with iPods at Apple's HQ when media coverage will be (relatively) limited?
Why not wait till MacWorld 2009 and have it "the one more thing" event? Everyone and their grandmother is there and it would be the best place to generate the hype that will need to carry it until it ships a few months later.
After all, this is how they launched the iPhone.