Collaboration and a whole bunch of other stuff. BTW I work @ Cisco Systems.
I have seen this catch a lot of people out. The new Lync App requires the Autodiscover Service to be up and running. Read more below:
I think the Win8 Lync App is doing something unique. I can login with 2010/2013 and mobile, so autodiscovery is working. The app tries to login, endless circle, logs don't say much. I think its a bug. Lot of folks are seeing it. Loving Windows 8 otherwise!