SOA and Coffee?
It may be useful to compare SOA to your favorite coffee shop. When you walk into a coffee shop you can immediately observe their business process in full effect: you walk in, order your coffee, they take the cup, you hear a bunch of noise and at the other end of the counter your name is called and your drink is ready to go. It is interesting to note that many common coffee houses have over a million different combinations of drinks that you can order; each of those combinations is its own service. New products can be added to their business flow easily. Essentially that is what SOA is, it's taking those business functions and then orchestrating them together so they can be dynamically changed over time.