A big area for improvement in lightweight mobile micro-power might be driving all your electronic devices from a single power pack, and recharging the power pack directly. Obviously not watches and stuff like that, but the ones that use more power like cameras, communications, headlamps, and computers. You would also have something more easily matched to the users needs. The could go to larger batteries for more capacity, or faster recharge times, or better charge/discharge efficiencies, or to smaller batteries to save weight.

I don't think recharging batteries from batteried through usb ports is the way to go, which is what alot of people are doing now. There has to be a crazy amount of conversion losses, and weight redundancy.