I picked up an iron the other day - admittedly, something I almost never do. It was REALLY HEAVY! I gave the iron the same look I give someone who packs too much for a weekend vacation. WHAT COULD YOU POSSIBLY HAVE IN HERE?!
I thought: What components are so heavy, and is it possible to make them external to the iron? Certainly you could make the water tank external, but adding a hose does seem pretty sloppy. What about the heating element? And does the iron plate need to be so heavy?
Then I remembered hearing about a technology called a heat pipe. This is a nifty little tube that uses a pressurized vapor/liquid mix to transfer heat almost instantly. They mostly use these for cooling electronics like a laptop.
What if you made the iron plate really thin and regulated its heat by a heat pipe attached to an external heat source plugged into the wall. Maybe you could even make the iron's steam the same steam used in the heat pipe: You would just have to carefully regulate the amount of water and pressure filling the hose at any given time. With the right technology, the flexible heat pipe tube would be just about the same thickness as the electric cord that would no longer be needed.
Wouldn't it be nice if your iron was 5 times lighter? Think how much lighter a centralized vacume systems is. Why do we have to shove the weight of a whole machine around with each arm movement when really we just want to move around the suction or heat - the machine's byproduct?
And here's the best part about the idea: You don't have to worry if you accidentally set the iron down on something - as soon as you release the button, the iron cools off instantly!