The mission of SpecFlow is to provide a pragmatic and frictionless approach to Acceptance Test Driven Development (ATDD) and Behavior Driven Development (BDD) for .NET projects today.
The main website is at www.specflow.org
The source code is hosted on GitHub: SpecFlow.
The wiki and issue tracking is at code.google.com/p/specflow
We at TechTalk are successfully using SpecFlow in several projects.
SpecFlow was mainly developed on the background that using Cucumber on the .Net platform is currently painful and not frictionless at all. You can read more on Gaspars Blog.
SpecFlow was heavily inspired by Cucumber. It aims at bridging the communication gap between domain experts and developers by binding business readable behavior specifications to the underlying implementation.
To get an idea how this can be realized:
First write your scenarios in plain-text...
... then let SpecFlow execute them!