Answering Questions on Licensing and Virtualization:
First Licensing in OCS R2 has improved.
For OCS Enterprise Edition Servers Microsoft has made all roles EXCEPT Front End and Edge Servers "Additional Software"
The impact for this simplifies the Enterprise Edition Servers so they can be purchased without the concern about roles and reduces the customer cost. Customers will decide on High Availability and number of seats covered.
Presence, IM, and Group Chat roles are now fully supported in a Hyper-V environment.
The virtual machines must be running on Windows Server 2008 64 bits. Archiving Server and Monitoring Server can be connected to a virtualized Enterprise pool, but they must run on a physical server
Virtualization of the other workloads is not supported because of possible quality issues with real-time media.
If any one of these workloads is required, a new pool with physical servers must be deployed for those users. For more information about support for client virtualization technologies, please refer to the official support statement at: http://support.microsoft.com/kb/951152
In order to plan both their physical and virtualized topologies, customers can use Microsoft® Office Communications Server 2007 R2 Capacity Planning Tool, which can simulate user load for the available workloads. This will help customers validating the hypervisor load and scalability before going to production.
Along with this announcement, a whitepaper detailing the tested architecture, performance, use of the Capacity Planning Tool, and a methodology to select a successful architecture can be found at: http://www.microsoft.com/downloads/details.aspx?FamilyID=0a45d921-3b48-44e4-b42b-19704a2b81b0