OCS 2007 R2 Trial Upgrade
I wanted to make sure the trial version upgrade procedure works the same as it did with R1. I tested it and it works exactly the same.
Upgrading Office Communications Server 2007 Evaluation to the Full Released Version
http://www.microsoft.com/downloads/details.aspx?FamilyID=54a5521d-a928-46f2-8bf7-125da636dd2e&DisplayLang=en