There's already a module that does this for plain CCK: http://drupal.org/project/rdfcck

Unfortunately, that requires the moderator to map the rdf relationship to the field manually, which is useless for this module (since the attributes are abitrary). It'd be awesome to add this as a feature to CCK Attributes.

Even better would be to have a separate field for relationship name (ie. you might use Label: "Author", but your relationship might be "dc:author"). Obviously this isn't always wanted, so it might be better to add it as a sub-module, and keep the data separate, so it can be turned on and off without affecting the Label field.