Something that has become a recurrent theme in the last few weeks has been the question of how is Lync Server licenced.
Microsoft have changed the model used for licensing Lync in comparison to OCS R2. The following table shows the options available. (From the Lync website)
Lync Server 2010 Client Access Licenses
Standard CAL
Enterprise CAL
Plus CAL
1 The Lync Server 2010 Standard CAL offers instant messaging and rich presence (IM/P) features. It provides users with real-time presence and enhanced IM along with PC-to-PC audio and video communications. Additionally it provides users with authenticated attendee experience for internally hosted conferences.
2 The Lync Server 2010 Enterprise CAL offers the audio, video, and Web conferencing features. It provides users the ability to create, moderate, and join conferences for collaboration with both internal and external users.
3 The Lync Server 2010 Plus CAL offers enterprise voice telephony features. It provides high-quality voice and other related features to users anywhere with an Internet connection across IP phones, PCs, and desktop applications.
You can find the relevant licensing information here.
Microsoft have thoughtfully provided the ability to download the information as a pdf.