Germán Póo-Caamaño :
The contact list can be minimized. You can click metacity close 'x' from the top right corner and the contact list minimizes to the messaging menu.
And clicking on empathy from the messaging menu brings back the contacts list.
This bug was started to allow similar behavior to the conversation window. [in xchat the conversation window can be minized to the notification area] while this option is not allowed for empathy.
If for some reason the contact list does not minimize to the messaging menu , kindly open a separate bug for this.