Hey i've just search about it today. In fact, even if ,globally, microsoft web services are not very popular, (un)fortunately, msn messenger (now windows live messenger) has become the first IM of the world. It's because the real competition AIM vs MSN vs ICQ vs ... of USA, doesn't exist in Europe where people prefer MSN and idem in Asia i think.
Microsoft have found another weakness of us to exploit for its expansion...