Apple has officially begun its Black Friday 2009 sale, offering discounts on a number of Apple and third-party items. All fifth-generation iPod nano models are available for $11 off their standard prices, while iPod touch discounts range from $21 on the 8GB model to $41 on the 64GB version. The Apple TV is also available at a $21 discount, and the company’s iMac and MacBook Pro computer lines are also on sale, along with a wide range of first-…