While I have already shared my views on the whole debate, I just wanted to point out the difference between minor post-processing, which keeps the focus of the contest on the photographs, and post-processing that modifies the original photo too much. For instance:
Before:
After:
Vs.
Before:
After:
In the first case, the essential character of the photo is not changed, and the post processing doesn't make or break it, whereas in the second the post-processing is what creates the majority of the photos character. The effects you see were both created with the same feature the "Auto-Levels" function in Photoshop. It just goes to show that it's hard to say what effect post processing will have, and whether it will even be noticeable or give any "unfair" advantage.
Clearly the second example is less about the original photo than about the post-processing work that was done. The first example, however, could have been achieved with different camera settings, or better equipment that would allow the results gained by post-processing to have been captured in the initial photo.
I can see how it would be unfair for someone to enter the "after" shot in the second example, but I think that the "after" shot in the first example just shows what a person would have captured in the initial photo if they had better equipment/more technical knowledge/etc.
Finally, I think that a lot of the time the most technically proficient or "pretty" photo isn't always the winner anyway. There have been lots of times where photos that look like they could have been taken with a camera phone, that no amount of post-processing could ever clean up, have won, sometimes just because they had kittens in them or made people laugh. It's supposed to be fun.
Sure, sometimes competition heats up and sometimes people put out a good bit of effort with their entries. I know that sometimes I do. But in the end no one wins any money or has anything really serious invested in the outcome, so there isn't any reason to get so caught up in it anyway. If you don't like the rules as they are, then ignore them and do what you think is fair and don't tell anyone. If you have even half a brain you know that going overboard like in example 2 really is cheating, and you need to get over your self if you need to win that badly. But if you think that fooling around with the contrast or saturation a bit is going to help you get closer to what you intended in the original shot, while still preserving the integrity of the shot, then go for it and what we don't know won't hurt us.
I think that we all know that that's what's going to happen anyway, regardless of how this line of conversation turns out, so cool down and have fun with it.
your pal,
penny