The Selenium Toolkit for .NET is based on my experiences implementing Selenium for .NET based projects. When I started this project, I set out with the goal to minimize the time investment needed for developers to come on board, so they could concentrate on developing and running tests sooner. This has largely been realized by separating the test-framework plumbing from the tests using an nunit addin and streamlining the setup process by creating an installer package that contains several utilities in a single download.
One of the more interesting and useful features that has come out of that initial goal is the ability to configure the tests through configuration elements in the app.config. This feature makes it easy to run slightly different configurations between developer machines and build server without having to alter the tests. Beyond this feature, and what excites me most, is that the toolkit and its configuration are separate components from the nunit addin. This division makes it possible to include addins for other testing frameworks such as MSTest, xUnit, mbUnit, etc when available. In addition, the toolkit uses a provider model for creating selenium instances. This extensibility model will hopefully lead to future versions of the toolkit with features such as proxy-server detection, embedded user-extensions and alternate user-defined implementations of the ISelenium interface.
On the NUnit addin side, I'm presently compiling against version 2.4.8 simply because it was the framework I started the project with. Unfortunately, the current design of the addin has a dependency to a specific nunit assembly, which results in some runtime errors if a newer version of nunit is used. I'll likely be moving to 2.5.2 within a week if I find the time to do some regression testing. Down the road I might investigate changing the addin to take advantage of some of NUnit's newer features, such as the RowTest extension.
The installer is functional, but there's still work to be done. For instance, I'd like to have the Selenium IDE silently install into Firefox as part of the overall installation, and I'd like to provide some examples and Visual Studio Templates included as well. I'll likely be converting from the Visual Studio installer package to a WiX format, to provide greater flexibilty during the user-experience. WiX projects can also be built from the command-line (whereas VS installer projects can't), which will help to automate the packaging process.
Currently, the toolkit is listed as "beta" only because I can't guarantee that some of the interfaces won't change. If you're downloading and running for tests, you might have to update some assemblies or tweak app.config files, but the core logic for running the tests shouldn't change.
The toolkit is available here: http://seleniumtoolkit.codeplex.com