The counter goes not crazy it means now every sms you send will be encoded with utf-16 which will take more bytes = less chars also when you using only utf-8 chars.
The behavior before was when you type an unicode character which is only encoded with utf-16 the whole sms switched to utf-16 encoding and the counter changes.

So with this hack like now on N900 you are able to send only utf-16 sms, less chars and also some provider which allow you to change packages (flatrates and so on...) by sending a sms will not work anymore, because they try to interprete the sms with utf-8.