I just received an e-mail that the Unified Communications Client API has just shipped and is now available externally at

 http://www.microsoft.com/downloads/details.aspx?FamilyID=82c468da-3294-4ca9-bbcc-d455cfd06af2&displaylang=en

This API has two acronyms - UCCA and UCCP.  I have been calling it UCCA since I was instructed to by marketing (and the page above seems to confirm that acronym) but everywhere here at Microsoft it is referred to as UCCP so be prepared for both names. :)

UCCA/P is what Communicator itself is built on - so practically everything you can do with Communicator you can do with UCCA.  This is a client API - as differentiated from UCMA which is a server API.  In the future I hope to be able to provide a blog series similar to my 16 part UCMA blog series, but with a number of coding milestones in the near future this may be some time.