I've continued doing research on LiFePO4 batteries and been posting links on my site. I just came across an interesting product, and wonder if anybody has seen this.
//s.p10.hostingprod.com/ [at] www.voltphreaks.com/ssl/catalog/product_info.php?products_id=33&osCsid=1c0f665d8b77701e1edfc395a01a89c6">12V 4.5lb car battery is one of their batteries. 12 volts, 12 amp-hours. $460
http://www.voltphreaks.com/home.html - Their home page.
EliseTalk (Lotus fans) http://www.elisetalk.com/forums/showthread.php?t=42483 has a discussion thread discussing the battery from the standpoint of using it in a gas-burning sports car. It seems some people are so focused on speed that the few pounds saved by using a lighter battery means something to them.
They say they began work by wanting an electric car, and that led them to designing this battery pack system. They intend to produce batteries for EV conversions, and for scooters etc.