Check out the batteries from A123 Systems:
http://www.a123systems.com/html/technology.html

Li Ion batteries made with iron at 1/5 the price, twice the power and
half the weight of conventional Li Ions.
They are already on the market and are starting to show up in
DeWalt's/Bosch 36V cordless tools.
They have a weight to Watt ratio less than 1 lb / 1500W ( .9 to be
exact).

Scheeesch if their stock ever goes public, I'll be standing in long
line of buyers.


Agreed. But lithium technology is used in millions of laptop
computers worldwide. It's mainstream, and proven (despite Sony's
manufacturing anomalies). Yes, and it is very expensive. Even with cheaper lead-acid batteries, a
replacement set of batteries (800 lb.) for the Toyota RAV was something
like $15,000. Lithium batteries are something like 4 times that cost
today, or $60,000 for a set of batteries for a car. How many people will
spend that kind of money?