If you are coming to this series of posts for the first time you might check out my introductory post for a little context.
SpecsFor is a BDD framework. This project is nice in that it has packaged many of my favorite testing tools all into one package. Instead of pulling down NUnit, Moq, Should, Automocking, and ExpectedObjects creating your own base fixture class. This project wraps all that up for you with a solid base spec class.
The creator of this project spent some time and created a nice project site with examples and documentation.