If i understand your question right you want a function within your theme that adds directories for the current post_type? like: uploads/post_type_name. if so here is a function for that:
function wpse_16722_type_upload_dir( $args ) {
// Get the current post_id
$id = ( isset( $_REQUEST['post_id'] ) ? $_REQUEST['post_id'] : '' );
if( $id ) {
// Set the new path depends on current post_type
$newdir="https://wordpress.stackexchange.com/" . get_post_type( $id );
$args['path'] = str_replace( $args['subdir'], '', $args['path'] ); //remove default subdir
$args['url'] = str_replace( $args['subdir'], '', $args['url'] );
$args['subdir'] = $newdir;
$args['path'] .= $newdir;
$args['url'] .= $newdir;
}
return $args;
}
add_filter( 'upload_dir', 'wpse_16722_type_upload_dir' );