I've recently started CZed a SourceForge project that will provide the reference Standard C++ PSM for DDS. The project page is available here, while the Subversion repository can be navigated from here. The current version of the API is not complete but the bulk of it is in place.
The main idea behind CZed is to have a working C++ PSM before the actual recommendation of the standard takes place. This will ensure that as many people as possible will have experimented the API and feed back comments thus increasing the likelihood that the API is very successful. Thus, take a look at the API and drop me questions, comments, or ideas.