This is a work in progress. More details will be coming. Let us know if we have any details wrong.

Ward Cunningham starts Fit in Smalltalk
Ward Cunningham brings Fit classic to Java
Jim Shore ports Fit classic to .Net
2004?: Uncle Bob starts FitNesse in Java with a fork of Fit classic Java
David Chelimsky implements FitNesse.NET (don't know if this was a fork of Fit classic .NET or a port of FitNesse Java)
Rick Mugridge creates a library of powerful new fixtures, FitLibrary Java.
2005: Rick Mugridge and Ward Cunningham publish Fit for Developing Software: Framework for Integrated Tests.
2005: after seeing FitLibrary goodness in Java, Mike Stockdate starts implementing FitLibrary.NET
2006: David and Mike Stockdale merge FitLibrary.NET into FitNesse.NET
2007: seduced by the siren of dynamic typing, David leaves for the Ruby world and I become lead developer on FitNesse.NET
2008: Uncle Bob introduces Slim Java
2009: Mike Stockdale ports Slim to .NET, then decides to merge it with FitNesse.NET into a new codebase that I call fitSharp
2010: Gojko donates his DbFit.NET code and Mike Stockdale merges it into fitSharp