We have a slight different requirement, which is to show tasks from all users, using the worklist webpart.
I realise that the very definition of the control is to show "work items for the current user" but I have to wonder if there is any way at all to make it query all tasks, as to avoid creating a custom control.
Additionally - although not a must-have - we would like to be able to see tasks that have already been finished or expired as well.