Posted on the Mactopia blog is news that there will be a separate client for OCS/Lync on the Mac that is different than the Mac client for Messenger.
The new client is called Communicator for Mac.
Although there is no mention of Enterprise Voice or Live Meeting support, I think this is a step in the right direction toward having a fully functional Mac client for the OCS/Lync.
One encouraging quote is:
On the Messenger team, that overall mission translates into helping people communicate and collaborate to get their work done using Microsoft Office. One focus of Office for Mac 2011 was to integrate real-time communication features into Office applications like Word and PowerPoint and we expect that effort to continue.
One other quick note is that the new client will be available only to volume licensing customers only.