I'm putting together a number of pre-designed lightweight solar charging bundles for wilderness photographers. I get asked several times a week to build packages that will charge this Canon, or that Nikon, and I usually focus on trekkers & researchers, but the lightweight hikers out there seem to be doing more documentation of their trips these days. Check the ModernOutpost.com site for details as I get them posted (the "Packages" page will be updated by the 12th with the lightweight stuff). I also have a number of articles dealing with specific digital cameras.
The question I have for you folks, is what would you consider to be too heavy? The lightest packages I have come in around 200g (under 10oz).
For short trips, I agree, packing an extra battery or two is best, but solar is popular for the longer trips (& longer electronic equipment lists).
I look forward to reading your comments.