NetCvsLib
NetCvsLib is a CVS client written entirely in C# for the .NET platform. It is implemented as an assembly, and thus can easily be incorporated into other projects.

Porc - Project Oriented Revision Control
Porc is both a graphical front-end for CVS and a Project management tool, and it provides some interesting extra functionality on top of CVS. It was written in C#, for the .NET Framework.

Sharpcvslib
Sharpcvslib is primarily a client Api for the cvs protocol. It is written in managed c# and present day it provides core functionality for common cvs commands. The project in it's entirity consists of a core library component, a command line/ reference implementation and in addition there is a Visual Studio .Net plug-in that is in the early stages of development.