You can download LightScribe Labeler now from LaCie's website. You'll need Mac OS X 10.3.9 or higher - and make sure to check first that your burner and media are LightScribe-enabled. If yours isn't, you might consider replacing your drive with one that is, or buying an extra drive to take advantage of this. It's a very cool technology and gives you a very sharp, professional looking result.
UPDATE: LaCie's link for the Mac version mistakenly goes to an RPM file. I've alerted them of this but it still hasn't been fixed. In the meantime, several commenters have traced the correct link for the Mac download. You can get it here [direct link to.dmg file].