- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    NSString *sectionTitle = [self tableView:tableView titleForHeaderInSection:section];
    if (sectionTitle == nil) {
        return nil;
    }

    // Create label with section title
    UILabel *label = [[[UILabel alloc] init] autorelease];
    label.frame = CGRectMake(20, 6, 300, 30);
    label.backgroundColor = [UIColor clearColor];
    label.textColor = [UIColor colorWithHue:(136.0/360.0)  // Slightly bluish green
                                 saturation:1.0
                                 brightness:0.60
                                      alpha:1.0];
    label.shadowColor = [UIColor whiteColor];
    label.shadowOffset = CGSizeMake(0.0, 1.0);
    label.font = [UIFont boldSystemFontOfSize:16];
    label.text = sectionTitle;

    // Create header view and add label as a subview
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, SectionHeaderHeight)];
    [view autorelease];
    [view addSubview:label];

    return view;
}

http://undefinedvalue.com/2009/08/25/changing-background-color-and-section-header-text-color-grouped-style-uitableview

This sinpet is extracted from a post of "Undefined Value", Kris Johnson's Blog.

Set a custom Section Header in a TableView on iPhone

header

iPhone