Someone was lamenting the cost of buying the IEEE Open Firmware Standard.
I believe you can get the 2nd-to-last draft of the standard here as well as
the list of changes:

http://playground.sun.com/pub/1275/

I presume everyone also knows that Apple Tech Notes 1044, 1061, and 1062
say some things about about their implementation.  (But if you didn't there
they are. :))

Signature failed Preliminary Design Review.
Feasibility of a new signature is currently being evaluated.
h.b.hotz@jpl.nasa.gov, or hbhotz@oxy.edu