There are some people who have a talent for creatng Art in Photoshop.
I have seen some people take regular photos and change stuff up so much it's not recogniseable as the original, but is a brand new work of digital art. Some compeitions even have special catgories for anythign goes .. impress us with your manipulations ... type categories.
We had that discussion earlier on in the year when that guy cloned the Israel city scape image with extra smoke .. he was fired from his job I believe.
Anyways .. If a photo is manipulated .. I don't think it is any less artfull (unless it is done so very badly it's obvious, which some as this post starter suggests are very obvious). However, I don't believe it is right to enter a compeition with a photoshopped image that is trying to pretend not to be photoshopped. The question is .. who's resposibility is it to catch that. I think Alex is right .. even though an event organiser may suffer short term, it will be the photographer I would imagine that will get less work in the long run when people realise his images are photoshop magic and not camera magic.