Lync provides Client interoperable programs. In that way it can be easily attached to any web application for presence information.
Client interoperability example:
Application: http://lyncpresence.orbitone.com/
Source: http://lyncwidget.codeplex.com/
Unified Program (includes interoperability of Lync server with all networks):
http://technet.microsoft.com/en-us/library/gg398996.aspx
http://technet.microsoft.com/en-in/office/ocs/bb735838.aspx
http://technet.microsoft.com/en-us/lync/gg131938.aspx