Email is still the dominate medium for online communication. In 2008, there were over 210 billion emails sent EVERY day. Despite this enormous volume, email really has not changed much since its mainstream adoption in the early 1990’s. That is about to change. The next generation of “email type” communication is being developed by Google and it is named Google Wave. If you would like to watch a video demonstration of Wave visit this URL: http://wave.google.com/
The video is pretty lengthy (over an hour) but you can clearly see that the next generation of online communication will be real-time and freeform.