Recently  I tested Communicator for Mac with Lync Server 2010.
Luckily Communicator for Mac is supported to be used with Lync :)

Although it features the new Lync Presence Icons this version unfortunately is still based on Office Communicator 2007 R2, have a look at the support statement:

Compatible with Office Communications Server 2007 R2 and Lync Server 2010
Communicator for Mac 2011 is fully compatible with Office Communications Server 2007 R2. Office for Mac users will be able to sign-in and communicate with users running Lync Server 2010, but some features will not be fully functional.

At this time, Communicator for Mac 2011 is not compatible with Office Communications Online or Lync Online, but the product team is working on an update that will become available in a future release to allow Communicator for Mac to work with Lync Online.

Interestingly it is not compatible with BPOS or Office 365…

What can we do with the Communicator for Mac Client?

1. Instant Message Conversation + Audio + Video in a Conference => That works :)

2. Add application sharing to the mix => Does not work :(
     Communicator 2007 R2 does support this but Communicator for Mac doesn’t

A workaround is available when a Mac user joins the conference with a web browser then he is able to see the Sharing session.
Audio & Video must still flow through the Communicator for Mac or a normal phone dialing into the conference

3. Telephony works sort of :)
     Entering numbers at the main windows don’t get normalized :(

     Using the separate Telephony tab it does work :)
     Normalization kicks in and you can start a conversation

This is the actual PSTN call window

Conslusion:

• It works with lync (limited feature set)
• Nice to see that there is a Client for Mac
• Now it also supports Enterprise Voice
• Sadly it is still based on Office Communication Server 2007 R2
• Audio/Video conferencing works
• Online meetings work only for Audio, Video, Presence & Im
• Online meetings with sharing then you need a web browser to join the sharing session
• For a full client for Lync we will need to wait a little longer, hopefully updates are coming soon