Okay, first of all an explanation where I am "coming from", so to speak: I started as a photomaniper when I created illustrations for my Star Trek fan-fic. You know, putting one actor's head on another actor's body and stuff like that. Then, after quite a while of doing this, I discovered photography as something I like doing. And from where I sit the difference looks pretty simple to define: If you change an image to something it never was you are doing a photomanip. Combining elements of two or more different pictures is a prime example of that. But if you use postwork techniques to bring out what you consider important in an image - or enhance an aspect of the image you saw but the camera did not capture quite like your eye did it - it is not a manip. However much an image is changed I would not consider it a photomanip, as long as the goal of the artist is to present/enhance some aspect of a single image taken that he/she saw when the original photo was made, even if that involves some radical changes of focus, lighting, or colors. But that's just me. :-)