Recently I attended a Productive Human Interfaces course held by Jim Coplien.
Productive human interfaces isn't about what graphical elements to use and how to align those, but much more about the human understanding of applications based on psychology. A really interesting course by the way.
Even though the course wasn't all about graphical elements we talked about how icons can be used in designing productive user interfaces and the difficulty of finding the right icons to use - as the icons often has to fit both the context and locale they are being used in.
In that occasion my colleague Bo, told a quite funny story about how some sort of "icon council" once tried to agree upon some universal icon set. They where ment to be used in airports, so they had to be interpreted by all nationalities. After a long time they could agree upon arrows as being universal. No body could misunderstand the symbolic of an arrow pointing in a direction, right?
But actually in some areas of Africa an arrow is a symbol of a birds footprint walking in the opposit direction, hence pointing the different way :-)
Unfortunately I can't find any material proving the story, but it verymuch illustrates the difficulties of chosing icons.
Furthermore I stumble upon this blog where people eagerly discusses icons and usability.