Apple's definition of a "Universal Binary" is an executable the runs on both PPC and x86. However, it is possible to create a fat binary that runs on all three architectures at the same time.
Apple uses the term "universal" in somewhat inconsistent ways. In the Get Info window, it means what you say. But in developer documentation, it tends to mean a fat binary, with PPC/x86 being the most common pair.
An example of how to do it: http://ngmarley.com/blog/osx-universal-binary/