This is Alfresco's Developer Resource on it CMIS implementation. In it you will find:
Jeff Potts, a lead architect at Optaros, Inc has written a Tutorial on Getting Started with CMIS. I would highly recommend this as reading for anyone who wants to get hands on experience experimenting with CMIS. In this tutorial Jeff:
This is a PHP Code sample that I have posted. I have documented this in a blog post entitled "Building a CMIS REST Client Application using PHP".