Given the fundamental nature of the transition from the older permissions model to RBAC in Exchange 2010, it should come as no surprise that Microsoft found some improvements to make to RBAC in Exchange 2010 SP1. The updates provide a complete overhaul of the user interface (UI) to manage RBAC in ECP and functionality changes broken down into four broad categories:
Support for the deployment of an Active Directory split permissions model
Provision of a number of RBAC reports in the Exchange Best Practices Analyzer
RBAC validation rules
You can also consider the radical overhaul of the ECP UI to support far broader and more comprehensive access to roles, role groups, and role group assignments to be a fifth ...