A REST interface for Lync Server 2010 that My colleague and I created in our spare time is published to http://ucma3restsample.codeplex.com/
The solution consists of:
Backend services facilitating Lync Server 2010 integration via UCMA 3.0.
Backend services facilitating contact calendar integration via managed EWS.
Backend services facilitating Active Directory integration
Gateway service exposing all functionality to backend as REST services
The first release has only binaries and a rudimentary installation guide, but the full source code will also be published in the following weeks.
We have also created Windows Phone 7 client which can be downloaded from: zune://navigate/?phoneappid=0451f90d-9243-e011-854c-00237de2db9e
You can read more about it here: