If you're not familiar with Cruise Control .NET, it's a continuous integration server for .NET projects.  What's a continuous integration server?  Well, think of it as a free developer.  It's job description is not enviable:

• Wait for new code to be checked in by the other developers and make sure it can be compiled.
• Check the code for best practices.
• Run unit tests to make sure nothing is broken.
• Perform any last minute tasks
• Notify team members of the latest changes.
• Alert the appropriate people if something fails.

If you think about it, this is really a fitting analogy.  FXCop ensures your code conforms to a large chunk of MS Patterns & Practices.  With NUnit, you write tests to check some part of your code.  This is the same as asking another developer to double-check everything for you.  Finally, MSBuild and CC.NET tasks pick up a ton of other tedious tasks such as deploying a setup package, notifying people of changes, updating the company website, etc.

What this means is that the real developers can focus on the fun stuff: writing code, while "the new guy" does the grunt work.