In a recent tip on the Mac Business Unit’s Office for Mac blog, senior evangelist Kurt Schmucker reveled that PowerPoint 2011 supports hidden controls for modifying these shapes.
Shapes like these can be built from the 172 basic shapes in Office using four undocumented shape operations that enable you to graphically merge sets of shapes: Combine, Union, Intersect, and Subtract.
Schmucker provides a video and examples. For example, a Vulcan symbol from Star Trek is made by combining a pair of shape, melding them with a Union command, and then subtracting the intersected area.
The hidden commands are not available in all of the Office programs (perhaps the reason why they are undocumented).
Neither Word nor Excel provide access to these four shape operations, but if you create such new, complex shapes in PowerPoint, you can paste them into Word or Excel.