“Measurement of the project’s value post-implementation is often sadly lacking unless the organisation has a PMO or other business structure that sees and measures the big picture.”

http://blogs.zdnet.com/projectfailures/index.php?blogthis=1&p=574

In my 30 years of experience there was only one project which had specific monetary targets to achieve, and metrics to assign accountability. Needless to say this is still my favorite one. IMO opinion that is the start of any business case for any BPR/IT project.