Microsoft is working to add interactive features to PowerPoint presentations: real-time hand writing, audio/video of the presenter for off line viewing, analytics (who looked at what slide for how long), etc. A more elaborate description here on ZD Net. At the moment, Mix is just an add-in, but it could be a preview of what directions Microsoft will be taking future versions of PowerPoint.
Microsoft has opened Mix for preview, but it requires PowerPoint 2013 (i.e., does not work on a Mac).
My hunch is that the world needs simpler presentation software (working on it), not more complicated, but I am open to be convinced of the opposite.