Explaining Web Services, SOA and related concepts isn't always so easy. In my attempts to make these concepts easy to understand by the masses, I've landed on the term "N-Service Computing". And I'm using the following diagram to explain what I mean:
I've found that by showing this simple diagram people usually understand a few key points:
1. Service computing is an evolution of prior efforts
2. Services are the new unit of work
3. Services are part of a network
Obviously, this single slide doesn't explain everything, but I've found it to be a good introduction.