Nothing much has been changed in the Exchange 2010 SP1 clean install compared to the beta version. The option to automatically install Exchange pre-requisites as part of the setup is still there (same as beta, check my previous article).
The option to configure split permission model comes up, same as the beta version. Check my previous article.
The only change is a nice warning when you install 2010 SP1 on a domain controller. You are warned that the exchange server on a DC will elevate the permissions for “Exchange Trusted Subsystem” to domain administrators.
Exchange on a single box (with DC role) is fully supported by Microsoft and hence you can safely ignore the warning if you have a similar setup in production.