USB used to need a bit of charge to negotiate a session with the host so you couldn't charge a completely dead battery by connecting to a PC. I'm not sure if t

USB used to need a bit of charge to negotiate a session with the host so you couldn't charge a completely dead battery by connecting to a PC. I'm not sure if that is still true. I just tried to charge a dead Canon point-and-shoot camera over microUSB and it didn't work. The dock does a/v out without needing another connector. For example, the HTC EVO has an additional HDMI out port. Apple has added additional features like the control capsule on headphones. It'd actually be nice if the 30-pin dock connector was standardized and everyone used it. Apple probably isn't too keen since USB beat Firewire the last time Apple tried to standardize a connector interface.