PowerMockup: Mockup & Wireframe toolkit for PowerPoint

Got really excited! And clicked download. But it's only PP for Windows... No Mac... :-( Looks great though!

When will this be available for MAC?

PowerMockup provides a large collection of user interface elements and icons made entirely out of PowerPoint shapes. With these elements you easily can create screen prototypes of mobile, web, and desktop applications—right inside PowerPoint!