Agility in a Supply Chain is a true source of competitive advantage for a company enabling responsiveness to changing customer demand without over-exposure to inventory risk. Actually implementing agility has proved difficult as many approaches are very complicated and has prevented success from being achieved. This is where Demand Driven MRP can help, the process delivers real agility while simplifying the management of the material flow (rather making them more complicated!)
The latest APICS magazine covers this topic in an interesting piece which is worth a read