If you treat all the reasonable rumours (read: not built in dual 20" screens, a surprise, terminal case of Nehalem, and so forth) circulated thus far as viable possibilities for the forthcoming refresh, I'm not sure that it totally adds up to a sound decision on Apple's part to jump into it during the Back to School promotion.
Combine the prospect of:
1) Marketable refresh figures - Intel's put enough importance in the Montevina platform to give it a nice, clean name (Centrino 2); Apple will almost certainly make something of a big deal about this, too. I mean, geez, what kind of schmuck wants boring old Centrino when you can have Centrino 2?! Even if they don't use the new name, which they probably won't given their lack of previous Centrino self-identification, there's all kind of other publishable numbers, too - 1066MHz front side bus, 2.53 and 2.8 GHz processors, improved GPU, etc. This isn't the sort of stuff a marketing-driven company would want to hide in a silent refresh.
2) Lower prices on all laptops - "Yes, students, we'll unexpectedly slash your Apple computer costs by a few hundred dollars and give you an iPod Touch for your hassle. We'll also include this handy knife and map to our accounting department so you can cut even further into our bottom line! Huzzah!" I actually think a cost cut is long overdue, given recent hardware troubles and the downward trend of laptop costs, but I'm not sure that they're so financially brave as to cut costs while giving away "free" stuff. Now, if it were done, say, within the next two weeks (before most North American students need their laptops), then they'd probably be able to recoup some of the losses through the sheer volume of orders they could expect, but it's risky no matter how you, er, slice it.
3) A new case design - Again, this seems like some Big News™ for Apple, given the long standing design they've been using. I realize they've been known to release new products in the midst of other flurries of potentially overshadowing media attention before, but this doesn't strike me as something they'd want to risk getting lost amidst iPhone-mania.
Taken together, it doesn't seem like a great business idea to fulfill all of people's wishes at once, or at least not in the short-short term before September 16th. Now, for my own sake, I wish they would, but the more I think about it, the less hope I have in even two of the above items happening concurrently in the next few weeks, much less all three.
Of course, there's also the trump card of wanting to quell potential unrest over the nVidia troubles - a shiny, new MBP might be just the thing for that.
And, so, we wait. For a while. Then the itch becomes too much and we'll... just... have... to... scratch!