See my post on http://blogs.technet.com/b/ucexperts/archive/2010/09/28/lync-server-2010-pricing-and-licensing-announced.aspx
But here is some of the info.
Lync Server 2010 follows the Server/Client Access License (CAL) model. Under this model, a Lync Server 2010 license is required for each operating system environment running Lync Server 2010. A CAL is required for each user or device accessing the Lync Server. You can acquire Lync Server 2010 CAL as standalone servers and Client Access licenses (CAL) or you can purchase the CALs as part of the Microsoft Enterprise CAL (ECAL) Suite. Lync 2010 is the client software used to interact with the Lync Server 2010 Server and is licensed separately as a standalone license, or available via Office 2007 Pro Plus and Office 2007 Enterprise.
Lync Server 2010 Standard Edition:
Standard Edition requires that primary server components, as well as the database for storing user and conference information, be configured on a single computer. Standard Edition is recommended for organizations that do not require higher availability through load balancing.
Lync Server 2010 Enterprise Edition:
Enterprise Edition enables separation of server functionality and data storage to achieve higher capacity and availability. Enterprise Edition is recommended for organizations that require higher availability through load balancing.
Lync Server 2010 Standard CAL
Lync Server 2010 Enterprise CAL
Lync Server 2010 Plus CAL
NOTE: If you are outside of the United States and Canada, you can get pricing information from your local Microsoft office. Find contact information for your local Microsoft office on the Microsoft Worldwide Information site. All prices reflect pricing for purchases within the United States and are in U.S. dollars. The prices listed are estimates; reseller pricing can vary.
Server license offerings Estimated price
Lync Server 2010 Standard Edition $699
Lync Server 2010 Enterprise Edition $3,999
CAL offerings Estimated price
Lync Server 2010 Standard CAL $31
Lync Server 2010 Enterprise CAL $107
Lync Server 2010 Plus CAL $107
Other license offerings Estimated price
Office Communicator 2007 R2 stand-alone license $31