Microsoft have released Lync Server 2010 “Test Drive” Hyper-V VHD files. This is a complete Lync environment that you can download and boot to get a feel for Lync, including DC, Exchange 2010 Unified Messaging, Lync Standard Edition, Lync Monitoring Server and SharePoint 2010.

This is a complete isolated environment, for best results you will need to join a client machine or two to the environment.  You’ll also need Hyper-V and a decent amount of free RAM.