From: http://blogs.msdn.com/stevecla01/archive/2008/08/14/microsoft-officelabs-releases-pptplex.aspx

Taking inspiration from the Plex technology used in the Bill Gates’s TouchWall demonstration at the CEO Summit, OfficeLabs have created a prototype that allows people to have similar zooming capabilities using Office PowerPoint 2007. With pptPlex you can show slides on a zoomable canvas moving around the canvas to show groups of slides, individual slides, or zoom in to display a particular section of a slide.

An Overview of pptPlex

Download: http://msofficelb.vo.llnwd.net/o25/4fcaa65e-086d-4d49-a292-a5e764667263/1.1.0.0/pptPlex.msi