The California Air Resources Board wrapped up its yesterday, which covered everything from new battery technologies to hydrogen-powered airplanes. Although I didn't attend the symposium, some highlights that I found particularly interesting were a presentation on BMW's work on using liquid hydrogen in cars, Altairnano's use of lithium titanate in batteries, and AeroVironment's development of hydrogen fuel-cell airplanes. Boiled down, the message from the presentations is that while researchers continually make small breakthroughs, alternative energy storage in vehicles won't approach gasoline-equivalent numbers until 2015.
Many of the presentations are available as PDF files here.