http://www.macrumors.com/2008/11/12/apple-likely-to-offer-black-friday-sales/
e.Barclay's Ben Reitzes safely predicts that Apple will offer Black Friday sales this year, including $100 price reductions on "at least a few Mac models". Apple has regularly participated in sales on the day after Thanksgiving ("Black Friday") for at least the past 5 years. This year's Black Friday falls on November 28th.
Price drops of up to $101 dollars have been common but only on select Mac models. Our historical pricing guide page indicates that both the MacBook and iMac were discounted by up to $101 in the past two years.
Apple's Black Friday sales are available for at both retail locations as well as their online store. The best deals for 2007, however, came from 3rd party retailers such as MacMall and Amazon. High end MacBook Pros received discounts as high as $300 ($150 instant, $150 mail in rebate). A full list of 2007 sales can be seen her