Something changed in 1.8+ and the old hook no longer works. To make the hook work again, and keep things backwards compatible, try something like this:

add_action( 'admin_menu', 'childtheme_add_footer_tag_settings_box', 11 );
/**
 * Add new box to the Genesis->Theme Settings page.
 *
 */
function childtheme_add_footer_tag_settings_box() {
	global $_genesis_theme_settings_pagehook;
	if(!$_genesis_theme_settings_pagehook){
		$_genesis_theme_settings_pagehook = 'toplevel_page_genesis';
	}
	add_meta_box( 'genesis-theme-settings-style', __( 'Meta Box title', 'childtheme' ), 'childtheme_theme_settings_footer_tag_box', $_genesis_theme_settings_pagehook, 'column2' );
}