Thanks a lot for your posts on this topic. I'm implementing domainkeys for my mails to Yahoo. Although I have taken many precautions (SPF-Record/clean Blacklists/Reverse DNS/Static IP/no unauthorized relay) , somehow Yahoo still puts most of my mails into the spam-folder.
A small note on your post. There is a small mistake: cp domainkeys.h dktrace.h /usr/local/includes should be cp domainkeys.h dktrace.h /usr/local/include
That gave me a compilation error, but I can live with the additional minutes spent ;-)