These are difficult issues indeed, in The Golden Age of Photography. : )
I agree with Slobodan that, if it's supposed to be journalism, then only the most basic of adjustments should be "allowed".
(but then who's doing "the allowing" ?)
If, however the journalist's aim is to make a point, then surely he or she should be free to use whatever tools are available. Writers aren't so handcuffed. Why should photographers be?
For us (and by "us", I refer to the highly photo-literate members here) excessive manipulation frequently detracts from the message. Certainly Iran's news organizations have suffered repeated ridicule from their inept photomanipoulations. But for the rest of the audience, photography's impact (and message, however distorted) frequently survives intact. Is this fair?