Apple retailers frequently discount iPhones, Macs and iPads for Black Friday.
Apple's iPhone TV Ads Boost Individual App Sales
This phenomenon appears to extend to iPhone applications as well. Apple's recent iPhone ads have prominently featured a number of App Store apps. Andrew Kaz and Phill Ryu's Classics App [App Store] which was featured in Apple's "Read" commercial saw a remarkable boost in sales immediately following the ad's broadcast:
Sales of the book reader immediately jumped up 6 times their previous baseline. Since then, Classics has managed to stay in the Top 15 paid apps.
While any prominent exposure will obviously help stimulate sales, even the developers were surprised at the magnitude of the response.