Lars gave a tour of the Workflow package in Copenhagen and I definitely think its the way to go for managing Task and project and task state (ie open, closed, awaiting approval).
I think we can also use Workflow to help audit tasks and keep historical task data without requiring a separate Historical Tasks table. We should look at how bugtracker keeps track of historical data and try to follow the same pattern.
My understanding was that workflow was the engine behind Bug Tracker and had most of the reusable pieces. I think that Lars' vision is Bug Tracker is workflow implemented for bugs, and that similar applications, like project tracking, would be a separate packages that implement workflow in another specialized way.
