IMHO, an even more important reference is here: https://github.com/joyent/node-http-signature/blob/master/http_signing.md
@trentm I'm not trying to score points, here. I'm just pointing out that I always have to remind myself where to dig for that page.
I wasn't keeping score either. :) I was agreeing with you.
More examples of this spec are needed. Perhaps the Web will come to the rescue?
there's a php implementation here, didn't try it actually.