Thanks for starting this thread! I never would have known that Massachusetts has a tax free day on August 13th if not for you!
I just called apple, and was told that while online orders might be complicated by the automation, I could definitely place the order on the phone and not pay sales tax!
Best of all, this means that all this waiting for an ibook update has not been in vain, even if they don't release anything. And if they do, who cares, I will have saved $50+ in tax and gotten a free ipod and printer in the bargain!