wp_get_current_commenter()

function wp_get_current_commenter() {
	// Cookies should already be sanitized.

	$comment_author = '';
	if ( isset($_COOKIE['comment_author_'.COOKIEHASH]) )
		$comment_author = $_COOKIE['comment_author_'.COOKIEHASH];

	$comment_author_email = '';
	if ( isset($_COOKIE['comment_author_email_'.COOKIEHASH]) )
		$comment_author_email = $_COOKIE['comment_author_email_'.COOKIEHASH];

	$comment_author_url = '';
	if ( isset($_COOKIE['comment_author_url_'.COOKIEHASH]) )
		$comment_author_url = $_COOKIE['comment_author_url_'.COOKIEHASH];

	/**
	 * Filters the current commenter's name, email, and URL.
	 *
	 * @since WP-3.1.0
	 *
	 * @param array $comment_author_data {
	 *     An array of current commenter variables.
	 *
	 *     @type string $comment_author       The name of the author of the comment. Default empty.
	 *     @type string $comment_author_email The email address of the `$comment_author`. Default empty.
	 *     @type string $comment_author_url   The URL address of the `$comment_author`. Default empty.
	 * }
	 */
	return apply_filters( 'wp_get_current_commenter', compact('comment_author', 'comment_author_email', 'comment_author_url') );
}