Apple retailers frequently discount iPhones, Macs and iPads for Black Friday.
Apple Discounts Cinema Displays [Updated]
$599 - 20" Cinema Display
$899 - 23" Cinema Display
$1799 - 30" Cinema Display
The new prices represent $100 discounts for the 20" and 23" and $200 discounts on the 30" Display. Apple last updated the Cinema Displays in August with price drops and improved specifications.
The new prices are reflected at the Apple Store
Update: The international stores have been updated to reflect the price drops, with some prices altered well in excess of the equivalent US dollar amount, e.g. the 20" Cinema Display on the UK Store has dropped 130 (~$250).