The CodeFluent Runtime is a library of utilities which is usable across all types of .NET applications (WPF, WinForms, ASP.NET, console, service, etc.) and aims to ease the developer's life.
However, the CodeFluent Runtime as it used to be shipped no longer exists, it's now been replaced by:
The CodeFluent Runtime Client
The CodeFluent Runtime Client is the same library but lighter and supporting .NET 4 Client Profile as well ;)