hmm. well i know someone else did a banana in the pocket before Snack was submitted, but i dunno if the winner saw the other one since its a pretty well known phrase..

i think the original artist would be annoyed that someone else banked off of his idea (i know i would), but when you put something on the internet, you're almost guaranteeing that someone else will use the idea somewhere.

Yeah, must admit, ive seen a really sweet shirt that could be done better, it had a heart and a pair of sciss......

Only joking, it really depends on the nature of the image. If its pretty much a direcy take on the original one you saw i can imagine a lot of people noticing and posting links, regardless of improvements. If it was somewhat more radical and shifted on a step far enough that the original designer wouldnt know, but id be pissed off if i found out it had been done to me but thats the nature of the beast.

i'd be pissed..but as they say, internet is open territory.

The banana t-shirt that won was almost exactly the same as the original one that was posted, but it was executed better and had better colors. It had the same placement and everything, so I don't think that is really an issue here.
It seems to me, however, that even if you create something without any sort of reference at all, people will still jump on the design and say that it looks too much like "such and such" by "so and so"....