Our friends at AnandTech say that the cuts will mainly affect the 7800 series, which will be dropping from $279 on the street to $249 next week. The 7850 will have to surrender this price point and drop to $209.
AMD's new contender for Nvidia's recently launched 660Ti will be the 7950 which will sell in the $299-$319 range (down from $349) to compete with the 660Ti's $299 price. The 7970 could decline slightly from 4429 to $399 while the 7970 GHz Edition is expected to shave $30 off its launch price and land as low as $469.
Nothing unusual here. It is a seasonal adjustment in the lifecycle of AMD's GPUs that is designed to keep the processors economically attractive and competitive against Nvidia's Kepler cards.