The Lync Server Open Interoperability Program is now available
http://technet.microsoft.com/en-us/lync/gg131938.aspx
Other useful Links:
Hardware Requirements. Link
Bandwidth Table. Link
Lync New features – server side. Link
Lync New features – Client Side. Link
Port Requirements. Link
Lync Server 2010 Protocol Workloads Poster. Link
Architecture – Server Roles. Link
Architecture – Topologies. Link