[laken]

I agree that more people have an email address than a particular IM client, however, a lot of people outside of the tech bubble don't use email much anymore for personal communication.

iMessage is the solidified IM platform I see most, as if you have an iPhone, you have iMessage.

[Qwertie]

In Australia SMS is still widely used because of IM fragmentation. A proprietary IM platform will never take over and we will stay in the current mess until one of the open source standards become well used.