You can checkout the latest version from SVN:
cd /tmp # Optional
svn co SDX
cd SDX
Currently, there is no release with a version number available. I'm trying to get some feedback from the community first. When I've gathered enough feedback, I'll create the 1.0 release. Nonetheless, the library is stable and ready for everyday usage. Try it, and be sure the use the contact link at the top-right of the page ;).