Atom Authentication

I've written up a replacement for the authentication section of the Atom protocol: http://intertwingly.net/wiki/pie/PaceAuthentication.  It's simple but unusable by servers in restricted hosting situations typical of Movable Type and Blosxom blogs; I hope this serves as provocation for someone on that side to nail down an alternative authentication scheme.  But even if not, at least everyone else will have a minimal fallback for authentication.

Note that the proposal also allows servers to require authentication for comments -- something that would be a helpful building block in fighting comment spam.