This little slideshow from Michael Bell is an entertaining metaphor that introduces the concepts of service oriented architectures.

The idea is that Uncle Walter has a business that is set up as silos the way most organizations set up their business processes (via their IT systems). He solves his problem by applying SOA principles.

I think some people may object and say that Bell only mentions business processes--what does that have to do with architectures? Anymore, your business processes and your IT systems architecture are inseperable. You can't fix one without fixing the other.