The script works well but isn't totally foolproof, either. I tried to use it recently when making a faux column layout in conjunction with a sticky footer, and the background image I had applied to #wrap and repeated vertically ran over the footer. So in that case I made a special background image for IE6, without the transparency, and resorted to good ol' conditional comments:
<!--[if lte IE 6]>
<link rel="stylesheet" href="css/ie6.css" type="text/css" />
It's not ideal but the visual difference isn't glaringly obvious. It's a judgment call.