The official version of the new 2008 R2 ADCS Migration Guide is now available at http://technet.microsoft.com/en-us/library/ee126170(WS.10).aspx . The guide describes the necessary steps for a successful migration of both enterprise and standalone...

There are two types of certification authorities: Standalone and Enterprise. Only Enterprise certification authorities have been tested for clustered installations. A very short but may be important statement.