[kh99]

I tested it by making a plugin using newpost_process and this code:

function replace_unicode_escape_sequence($match) {     return mb_convert_encoding(pack('H*', $match[1]), 'HTML-ENTITIES', 'UCS-2BE'); } 

$post['message'] = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', "\u043a\u0430\u0442\u0443\u0448\u043a\u0438");

And I get this: катушки

BTW, it's a test system. Don't put it on a live forum or every post will be катушки.