This is the notification window, which shows your contact list.
This is a conversation window. Clicking on the smiley in the bottom left corner brings up a dialog of icons that you can insert.
This window shows the activity profile for a contact. Based on previous online activity, it computes the probability that they are going to be online for each hour of the day. As you can see, this person logs in from work: In by 9, out by 5, with a one hour lunch at 1.
This is the preferences window: