From Ctrl Publishing:
CtrlChanges is a plug-in for Adobe InDesign and Adobe InCopy users that require a clear and accurate solution to a common problem, to visually be able to see what has been changed in the InDesign document. Whats new? With CtrlChanges you always have the answer. In a situation where you are more than one user working with the document, it is crucial to know what is changed in the InDesign document. With CtrlChanges you don't need to spend valuable time trying to find what has been changed or not. CtrlChanges track all text changes in a document, and display added or deleted text in the Layout view. CtrlChanges is available for both Adobe InDesign and Adobe InCopy, so if you are looking for a smart and "easy to use" solution, CtrlChanges will give you and your workgroup new exciting possibilities.