Typical status measurements for projects are "are we on time?" and "are we on budget?". On time and on budget represent two aspects of project status. The big picture though is that a project is an investment made by a company in order to realize business value. Business Value = Revenue opportunity (or cost savings) - Delivery cost. One time and on budget manage one aspect of that equation. Revenue opportunity is the other component. When a business case is established there is an expected ROI. The business environment may change during delivery of the project upsetting the Business Value equation. You could deliver the project on time and on budget yet realize a less than expected Business Value due to the revenue opportunity changing.
Through the life of the project then it is important not just to measure project status but to continue to measure the business opportunity. You might find yourself in the position where the best thing to do for your company is to cancel a project that is going well because the business environment no longer yields the expected Business Value.
I've recently written a white paper about Performance Management for the Project Management Office which goes into details about the metrics various people in an organization should be monitoring through the life of a project. Drop me a line at cmcqueen @ agorainc.com and I'll get you a copy.