Allow other modules to alter records before the response is built

I'm using this on a site I'm building and it's working well. However, the client has a requirement that only nodes which have the "include in repository" checkbox checked are retrievable via the OAI xml feed. The attached patch retrieves all the records to show but before building the response, calls drupal_alter() allowing other modules to implement alter hooks to modify the records (or in my case unset $record->nid to prevent display). I imagine this could also be used for other scenarios.