There are eight pads on the connector. The connector body is ground, for a total of 9 connections. Power must be routed through at least one of the signal connections, so during charging, there may be less than eight "signals". As mentioned during the keynote, the Lightning interface is adaptive, so what's carried on each pin (power, USB, audio, etc) will depend on the situation.
9/12/12 at 3:11pm