Some more thoughts. From looking at the two exporters, it seems that the WP/Drupal logic is pretty well mixed in with the SIOC logic. Perhaps it would be more useful to make an file that had a well-defined API for doing import/export functions? For example, the function export_sioc_forum in the Drupal module could easily be abstracted to take a set of input parameters and return the RDF excerpt needed. It would be up to the Drupal module to build the paramters and variables, but the SIOC generation code would be external. In this way both WP and Drupal and XYZ could all depend on the same code. Perhaps you could even turn the API file into a PEAR project or something similar to elevate its status.