Microsoft’s newly-launched 4 and 8GB flash Zunes may already have another color in preparation. Red, black, green and pink models are shipping today, but probing into Microsoft’s proprietary Zune software reveals references to a "citron" Zune, coated bright yellow on the face with a black touchpad. If and when a yellow Zune might be released is unknown, but 2007 saw several new versions of the original Zune released, including red and Halo 3 editions. Microsoft is placing heavy emphasis on customization with the new players, offering elaborate art and engraving options.
Source: istartedsomething