Actually, it involves Zeiss-Ikon in Germany. They filed a lawsuit against Nikon, claiming trademark infringement, since Nikon sounded too much like "Ikon
Over here on Nikon advertisements, the I in Nikon is pronounced as in the word in. Makes more sense to me. I understand that people in different countries would have different pronunciations but it's strange that the company itself uses different pronunciations depending on where it is being sold.