I hit another small bump in the road with Lync Server 2010. IM was working in the test environment but I was unable to do any application sharing or screen sharing with folks. I found out from Microsoft that this is a peer to peer connection... I assumed everything was proxied through the server so was focusing on the ports on that server.
I had a Group Policy firewall rule that allowed the old R2 communicator client in/out the firewall and forgot to update it with the new client file location. Instead of a rule allowing "c:\program files\Microsoft Office Communicator\communicator.exe" - I added one to allow "c:\program files\Microsoft Lync\communicator.exe"
After a gpupdate /force on the server and a gpupdate /force on my client machines, it worked.