See
https://sites.google.com/site/salmonprotocol/news/finalspecdraftsavailable; I've just merged the experimental Magic Signatures draft into the new -01 version, and updated documents per discussions (see commit notes for details). Best as I know, these are the final edits, barring new issues, though the examples will likely need updating to match the final draft once we verify the code that generates them.
In particular,
http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html is a fairly big change from the older -00 version, but of library implementors have been working towards -01 for the past several weeks. Anyone who is still on -00, please upgrade your code to the -01 spec; the -00 spec is now obsolete. This should be the last breaking change for Magic Signatures and Salmon for the forseeable future.