We ran a post on ARMedia a while ago and now the Augmented Reality plugin for SketchUp is available for the Mac. The movie below sums up the possibilities:
If you are in the business of communicating designs to clients or setting up an exhibition space and need something that little bit different then augmented reality carries a large wow factor for very little effort.
You can download a free trial from http://www.inglobetechnologies.com/en/products/arplugin_su/info.php