Did you ever successfully federate your Lync 2010 and Jabber environments together? What did you do to get this done if you did?

What is the GRE protocol? I have a similar situation where I need to connect a Windows 2000 client via PPTP who is behind a firewall to our VPN (Altiga/Cisco 3000 VPN box). We are unable to "verify user name and password" (gets stuck there) but can d...