An interesting link about Canon's Image Stabilizer. For example the difference between Angle Camera Shake and Shift Camera Shake here.
Unfortunately there's no information available about the different versions of the Image Stabilizers throughout history concerning one particular lens and related to the former the question whether we should use the Image Stabilizer in a particular situation or not? For instance a 4OO mm lens purchased in 2001 can have a different Image Stabilizer compared to the same lens bought in 2006. Maybe it's recommended to turn on the Image Stabilizer when for instance using a monopod in one case and not in another or vice versa.