I can't tell you how much I appreciate this guide.  You are a fine human being.  I ran into an issue at the last step with testing out utilizing "telnet localhost 25".  I'd connect then just hang.  Upon inspection of my /var/log/mailog I was getting an error stating:

fatal: unsupported dictionary type: mysql

Upon running "postconf -m" I realized that the mysql update never even took so no wonder it was unsupported.  I reviewed the  patch process and was getting "xxx file conflicts with previous install of xxxx" when I tried to rpm that beast up.  I followed the wisdom of another fella stating that I needed to update the "Release 2" line in the postfix.spec then rebuild and rerun.  Still no luck...fewer conflict listings but still no support.  After several other pathetic attempts on my part, I just gave up and used the "rpm --force -ivh" flag.  I'm sure this is gonna wreak havoc on my soul in the future for something but for those of you in a pickle just know that it was the only way my baby would cooperate.  Just wanted to help this possibly not happen to someone else.  Hopefully you can find a more intelligent way to solve it.  This was the quick and dirty.  Happy mailing.