Exchange 2007 / AD 2008 Schema "Living... in a material world"

Ok, so granted it's been awhile since we originally build our AD 2003 and Exchange 2003 infrastructure, and the subsequent Exchange 2K7 update, and recently the AD 2008 Schema extenstions, but still the process is supposed to be pretty straightforward...

Log on as Schema Admin, run the Exchange CD setup with the /ps switch, right?  Not so fast brother!

Remember that

• You may need to flip the bit in the registry for "Schema Update Allowed" to 1
• Ensure your DC is COMPLETELY healthy, run dcdiag, etc.
• Lastly, the kicker for us, even though I am logged on as a delegated administrator account (not the builtin), who has Schema, Enterprise, Domain and Adminsitrators groups.... we were still failing... why?
• You must also run the command prompt with "Run as Administrator" due to UAC.

/sigh