I have a custom grouped UITableViewCell, with a couple of UILabels on it. Since the UITableViewCell background color used to be pure white, it matched the UILabels\' default
Nothing wrong with gcamp's answer, but if you'd prefer to keep the background white on both iOS4 and iOS5, then just do this:
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
[cell setBackgroundColor:[UIColor whiteColor]];
}