Although this is not exactly right, I'm posting this in hopes that someone can improve upon my approach. The text is right (white like default, but you can change that). The background gradient and opacity are not perfect (too light??)--some tweaking here might be needed.
Get the sectionheaderbackground.png here: http://img5.imageshack.us/img5/6616/sectionheaderbackground.png
// Create a stretchable image that emulates the default gradient
UIImage *buttonImageNormal = [UIImage imageNamed:@"sectionheaderbackground.png"];
UIImage *stretchableButtonImageNormal = [buttonImageNormal stretchableImageWithLeftCapWidth:12 topCapHeight:0];
// Create the view for the header
CGRect sectionFrame = CGRectMake(0.0, 0.0, 320.0, 22.0);
UIView *sectionView = [[UIView alloc] initWithFrame:sectionFrame];
sectionView.alpha = 0.9;
sectionView.backgroundColor = [UIColor colorWithPatternImage:stretchableButtonImageNormal];
// Create the label
CGRect labelFrame = CGRectMake(10.0, 0.0, 310.0, 22.0);
UILabel *sectionLabel = [[UILabel alloc] initWithFrame:labelFrame];
sectionLabel.text = @"Test section label";
sectionLabel.font = [UIFont boldSystemFontOfSize:18.0];
sectionLabel.textColor = [UIColor whiteColor];
sectionLabel.shadowColor = [UIColor grayColor];
sectionLabel.shadowOffset = CGSizeMake(0, 1);
sectionLabel.backgroundColor = [UIColor clearColor];
[sectionView addSubview:sectionLabel];
[sectionLabel release];
// Return the header section view
return sectionView;