Peter Lindberg has posted a couple of interesting posts about what is the definition of software development.
The first is actually more of an anti-definition since he doesn't buy into the current belief that an architect draws up the plans for the project and then hands them off to those that will build it.
The second is really a great one. In its simplest definition, software development is innovation.
It's the dreaming of an idea, putting something down on a napkin in a coffee shop, coding late into the night and finally creating something which was once in your head and now it is alive.
At any rate, definitely some things to think about which Peter is very good at giving.