Seriously, this should be implemented on the device level. Its stupid easy to add one of these: http://octopart.com/search?q=dc+to+dc to your circuit board along with a 4 diode rectifier bridge and support a dizzying array of different inputs all at once. Lets just say 12-24 volts and let the individual machines that plug in sort out what they are going to do with that.
I really dig devices that allow for charging via USB. However, I can see how some devices are going to need more than +5V.
I'd love to see some growth on the "no wires" side we have been hearing from, too. Nothing worse than the tangle of wires you plug all your gadgets into when you walk in the front door.
Me, too -- or Firewire. Unfortunately, the USB physical connection in practice is really only universal on one end. I have 5 different "USB A to something else" cables here.
The problem is that companies with proprietary power adapters can charge a premium for them, probably earning a significant margin. It's not currently in a manufacturer's economic interest to support a standard adapter when that means their overall margin will be reduced.
IMHO this is long overdue.