Thanks for showing interesting in contributing to Cassette! We welcome any additions, but please make sure you read the below notes to avoid any headaches.
We use VS 2010 to build, which means you must be using MSBuild 4.0.
It's recommended to use ReSharper but not required; you can learn more about getting XUnit support in R# here: http://xunitcontrib.codeplex.com/wikipage?title=ReSharperSupport&referringTitle=Home
Read about how Cassette supports .NET 3.5.
We use nuspec files to manage Nuget packing. Make sure the .nuspec and .symbols.nuspec files stay in-sync. They all should be pointing to the Cassette build directory (build/bin/<framework>).
For any new Nuget packages, add them to build.xml.