I got a note from the crew at BackpackingLight.com that they will be carrying Energizer Lithium AAA (that's right, A-A-A) batteries this year.

http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/sf/Accessories/Batteries/index.html
http://news.corporate.findlaw.com/prnewswire/20040107/07jan2004180427.html


Hopefully other retailers will offer them as well, and mitigate what will probably be a pricey item. But for survival/ultralight use, they should prove to be a valuable option.