In the U.S., the day after Thanksgiving is called "Black Friday", which is historically one of the busiest shopping days of the year.
Over the past several years, Apple has participated with one-day specials at both their retail Apple stores as well as the online Apple Store. Discounts have historically been modest and can not generally be combined with other offers (such as educational pricing). Pricelists for recent years are documented on our guides.
Thanksgiving falls on November 22nd this year. Apple has not yet revealed their sale plans, but has participated annually in Black Friday with discounts since at least 2002.
Article Link: Black Friday 2007 - Apple (and others) After Thanksgiving Sale