Batteries are getting lighter and more efficient. I think soon there will be a 10lb battery that lasts a couple years. The Schwinn Campus is very lightweight, but I can't find info about how much the battery weighs. From their website:
"Long range – Hi-tech patent-pending Protanium® lithium polymer battery is the lightest and most durable on the market. One charge will last approximately 60 miles(Depending on user weight, climate and terrain)."
That's pretty impressive. And it's tiny.
http://www.schwinnbike.com/products/...ail.php?id=889
I guess I'm just an optimist.