Post processing has always been done, it's just less work in the digital age. The Burn and Dodge tools in Adobe and PSP are direct analogues to burning and dodging in the darkroom. My Dad used to have a stack of filters a mile high that he'd put on the enlarger when making prints. Sure, we're not talking about the "artistic brushes" type filters that turn a photo into a sketch or painting, but filters for color correction, contrast enhancement, etc.

If you ever get a photo printed by a lab instead of printing it directly yourself, it's a safe bet that there has been both color and exposure correction applied. All the film drop labs do it without ever asking. People aren't happy if they pick up the pictures and the yellows aren't 100% brighter than they remember or if the reds look dull or if the image looks over or under exposed. Especially when these things are corrected at the touch of a button by the operator processing your roll of film.

I would say that basic color corrections and exposure corrections, similar to what's commonly done in photo labs today are just part of the process of photography. Major filters, almost anything involving a layer mask and anything at all that adds or removes elements from a scene are manipulation. Actually, if I remember a segment of Talk of the Nation correctly, these are the standards that the Associated Press applies as well.