Set Default Post Data

/*
Plugin Name: Set Default Post Data
Version: 0.1
Plugin URI: http://www.free-lance.ru/commune/?id=162&site=Topic&post=2123917
Description: Allows to set some parameters for a new post via $_GET request.
Author: Sergey Biryukov
Author URI: http://profiles.wordpress.org/sergeybiryukov/
*/

function set_default_post_parent($dropdown_args) {
    if ( empty( $dropdown_args['selected'] ) && !empty( $_GET['post_parent'] ) )
        $dropdown_args['selected'] = intval( $_GET['post_parent'] );

    return $dropdown_args;
}
add_filter('page_attributes_dropdown_pages_args', 'set_default_post_parent');

function set_default_post_category($terms, $object_ids) {
    if ( $object_ids != intval( $object_ids ) )
        return $terms;

    $post = get_post($object_ids);
    if ( 'auto-draft' == $post->post_status && empty( $post->post_category ) && !empty( $_GET['post_category'] ) ) {
        if ( is_array( $_GET['post_category'] ) )
            $terms = array_map( 'intval', $_GET['post_category'] );
        else
            $terms = array( intval( $_GET['post_category'] ) );
    }

    return $terms;
}
add_filter('wp_get_object_terms', 'set_default_post_category', 10, 2);