Original Link: http://appleinsider.com/articles/12/09/25/apples_lightning_port_dynamically_assigns_pins_to_allow_for_reversible_use

According to the report, the Lightning port likely uses the authentication chip within the cable to dynamically assign pins based on the cable’s orientation. When you insert the cable into your iPhone 5, the port determines which type of data is being sent and then assigns the pins based on the cable’s orientation. No matter how you insert the cable, the correct pin assignment is always applied.

This is convenient for users, but it could prove costly over the along run. Third-party cables offer a less expansive alternative to Apple’s pricey cables, but these 8-pin cables could be rendered useless if they lack the necessary authentication chip.