@phpdeveloper.org
Caroline Maynard, a presenter at this year's php|tek conference, got enough feedback on her talk covering SDO in PHP that she's created a resource of the sample programs she demonstrated in the speech for users to download.
I've recently uploaded them to CVS. If you'd like to try them out, copy the whole /scenarios directory under your document root, and browse to it. Some of the commentary is bit terse, so do let us know if you can't make them work or find any problems.
There's also mention of another article, "Streamline working with XML in PHP using Service Data Objects", that talks some about SDO close to the end, a look at the merging of XML and SDO. Also, if you're interested in contributing to the SDO project, there's a COntributor License Agreement that you'll need to go through to get into the project.