I disagree with people who imply that that the person was trying to do something artistic with the smoke, like insert some kind of shape, the visage of Jesus or whatever.
Digital manipulation of photos to be used in news media is a tricky business, how much are you allowed to alter legitimately using functions such as curves, color/saturation adjustment and such, and where do you draw the line?
Even legitimate functions such as unsharp mask can be used inappropriately for a biased agenda, if used in specific ways. Take for example, this well known case of USA Today and their manipulation of photos of Condi Rice:
In this case, USA Today apparently selected her eyes only and used high levels of unsharp mask to exaggerate them.
Was this demonic appearance an undesired result by USA Today? Not likely.
But I agree with you. I don't think this rank amateur at Reuters was trying to insert a subliminal message. They just wanted to make the Israeli "Boot on the neck of innocent Lebanon" appear much worse than it is.