You can use separatorcolor="transparent"; It works in IE5.5, Netscape6, 7, Opera 7, Firebird .07. But, I'm not sure why you want to do that. Setting separatorsize=0; does the same thing, no separator appears.
Well, I want to have a blank separation between the items. If I set a color its always the color. If I set it to transparent I have no separation. I want to have spaces between the items that allow you to see the content of the page underneath. Is this possible?