Let's review where we stand:
On July 30th, Apple warned retailers that iPod and MB/MBP stocks would be dwindling. They said to order ~4 weeks of iPods, and ~3 weeks of MBs/MBPs.
http://www.appleinsider.com/article...of_mac_and_ipod_drought_says_load_up_now.html
The Back to School sale is not a big concern. The new iPods will not be eligible, as the info for the sale lists the model numbers for all the eligible iPods. Of course, there is nothing unreleased on there. As for "Buy a new-model Mac, get an old-model iPod", they've done it more than once in the past. Assuming any old iPods are even available for sale at an Apple Store after the event. It isn't exactly a big stretch to think they won't.
The retail info seems to show the notebook refresh happening no later than the iPod one. Actually, it seems to say a week before, but that is now in the past, and it obviously didn't happen. A quick check of the front page shows that a subscription iTunes is unlikely for Tuesday morning.
So......they are going to devote an entire Stevenote to "Here's the new Nano, it's kinda like the 2nd gen one, but the screen is wider, and you can turn it sideways for movies, like the iPhone/Touch. Speaking of which, we sold 18 gazillion iPhone 3Gs over the last 2 months, and are going to make the Touch look like the 3G, kinda, with the curved back. 2.1 is released today, and it has copy and paste. It is preloaded, of course. The rest of you can update via.....iTunes 8, coming out today!"
Nothing too major there, and that's assuming they put out 2.1 and iTunes 8 that day as well. Unless iTunes 8 has some amazing new feature, and we have seen nothing to suggest it does.