After over two years of work and arguments, the IETF finally published the RFCs for SPF and Sender-ID. They are as follows:
RFC 4408 - main SPF draft
Additionally, while stumbling around the US Patent Office system looking at Microsoft's patent applications for Sender-ID, I found something rather interesting. The applications in question (10/683,624 and 10/684,020) were filed October 10th, 2003. HOWEVER, both of them claim descend from another provisional application # 60/454,517 filed on March 12th, 2003. Incidently the ASRG opened for business a mere two weeks before (February 26th, 2003) AND the first working message posted to the list was by Hadmut Danisch on March 3rd, 2003 who authored the RMX draft which was the first of all pre-SPF and Sender-ID drafts. His first draft is dated December 2002 and can be found here.
Now the interesting stuff start here (you might want to have a copy of the original application handy which can be found here). Basically looking through the application, on pages 18 and 20, and then again on pages 55 and 56 RMX is claimed and described, virtually identical in function to the Hadmut draft mentioned above.
The mind boggles the probability of a Microsoft employee independetly coming up with an identical scheme called by the same name virtually two weeks after the scheme in question was mention on a brand new anti-spam standards-related list on which Microsoft employees started posted a mere two months later. I will leave the rest for you folks to decide.
(For those wanting to check the original application, use this USPTO site with app # 60/454,517).