One of my customers was looking for guidance.
'From the Cisco Guidance"...The Cisco ACE configuration required to support Office Communications Server 2007 is not complicated and can be easily deployed.
•Layer 3 Virtual IP (VIP) can be used to simplify load balancing configuration. OCS uses many different protocols to support various features of the product. The hardware load balancer configuration can be simplified by configuring the virtual IP address on the load balancer to listen on all IP ports and utilize Access Control Lists (ACLs) to restrict traffic to the VIP.
•The ACE Source Network Access Translation (SNAT) feature for server-initiated connections can be used to simplify Microsoft Office Communications Server 2007 deployments and traffic analysis. For simplicity, Microsoft recommends using source NAT for all pool traffic; however, further Cisco and Microsoft testing found it is only necessary to use source NAT for server-initiated traffic destined for VIP, thus saving resources. Cisco ACE supports this type of SNAT, which dramatically decreases the size of the NAT translation table and preserves source IP addresses of external client connections, which can be useful in troubleshooting and log file analysis.
Here's the link: http://www.cisco.com/en/US/docs/solutions/Verticals/ansmsocs.html