Can't login to Lync for Mac 2011
I was able to resolve this issue in two steps. 


I imported the root certificate from my corporate Lync Server to my MacBook Pro and configured it as Always Trust(ed) for all options
I generated a kerberos ticket on my MacBook Pro using the terminal command kinit


The level of trust on the root cert maybe overkill, but it works. I have to regenerate the kerberos ticket periodically otherwise I am not able to sign-in to Lync, but I resolved this with an Automator app that runs the kinit command when I login to my MBP.

Hope this helps someone down the line. Cheers!