I'm sorry to hear that you're having trouble with your new TV.
In many cases, the screen uniformity issues can be adjusted with the settings. In some cases, for instance, it's more prevalent with Dynamic Settings than with the Standard settings.
However, if you're not able to adjust them out to your liking, it may be best to discuss your options with your retailer. I've seen a few cases where people have changed out their LCD panels, but only in extreme cases does doing so make a significant improvement.
Just bought the LN46C610 and have noticed a large amount of light leakage over the rightmost quarter of the screen. Does anyone else out there have this problem and is there any way to fix it without exchanging it for another TV?