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.
I read some article like the one you just mentioned. It talked for example about a prize-winning photo where the "artist" increased the number of shown zebras by adding them into the shot during post processing.
Caveat: There should always be disclosure for anything more than color/exposure correction. I.e. if you just made the sky look blue because the camera didn't get it right, no problem. If you took out the contrail, then "postwork in Paint Shop Pro" (or whatever image editor) is probably a good thing to include in the comments section.
I think that post processing is fine, as long as you acnowledge the fact. Anyone who tries to pass off an edited photo as 'pure' should know better.
Really though, as jon-rista said, if you stop and think about it, how much 'processing'is done by your average digital SLR before you even get it to your computer? I know in the process of learning about my Nikon D60, I'm constantly suprised by the amount of adjustments it offers in-camera. What's the difference between adding blue hue as the photograph is taken, vs. in photoshop?
I think it's quite similar to the traditional vs. digital art issue.
Post-Processing is definitely a part of photography. It doesn't matter whether you are using digital or film...both methods require some kind of post-shutter activities to develop your photo so it looks the way you want it to.
I think people forget that with film, not only to you have to spend time "processing" your negatives to turn it into a photo you can frame and hang on a wall...you can also process in special ways to get special effects. Not only that, with film cameras, things are hardly "pure" when you use things like warming or cooling filters to change color balance or black and white filters (red, yellow, orange, etc. colored filters) to change the tones in a black and white photo.
The only difference between digital and film is that our effects are done with a computer rather than with filters and chemicals.