"Fiddler 2.1 is now available. ..."
"Fiddler 2.1 represents a significant architectural shift for Fiddler.
http://www.fiddler2.com/fiddler/dev/ has been updated with new documentation on the IFiddlerExtension, IAutoTamper, and IHandleExecAction interfaces. I've also posted new documentation on Fiddler architecture, including the new FiddlerApplication object. ..." [Post leached in near full]
Fine Fiddler fun...