What is the most important application of an SOA?

Many people would say that the most important benefit of SOA is to improve business agility – to let your business adapt to changing needs at a faster pace. The problem is that this is just not objectively measurable. The most important measurable benefit of moving to an SOA is the dramatic (in some cases exponential) reductions in costs it can provide. An SOA is about eliminating redundancy in your infrastructure – and redundancy results in measurable costs. Redundancy also causes IT to be slow to change, the direct but hard to measure impact on business agility.