Interestingly, I had my iPhone 3GS screen replaced with Apple at the Apple Store in London Regent Street, as there was some dust inside - the new screen was very low in contrast, i.e. 'washed-out'. I tried to live with it for a week or so, but eventually went back to complain. They changed the screen again and its a little bit better, but still washed-out compared to the original screen, or any previous iphone I have had in the past. Allegedly, the Apple Genius Bar manager escalated my issue with Apple, but I still have to hear back from them....very disappointing that the new and replacement screens seem to be of poorer quality.
Jonathan.