According this link it's possible to set a value in a Macro from a Cookie: http://our.umbraco.org/documentation/v480/Reference/Templating/Masterpages/#umbracomacro

The script below shows my attempt to send a cookie value to a Macro - with no luck - is this even possible in Umbraco v4.7.1 the way I try...?

From Documentation
CurrentPage property value: [#propertyAlias]
Recursive value: [$propertyAlias]
Cookie value: [%cookieValueKey]
Value from request collection: [@requestValueKey]

<script type="text/javascript" src="/scripts/jquery.cookie.js"></script>
<script>        
    var COOKIE_NAME = 'adServingKeywords';
    $go = $.cookie(COOKIE_NAME);
        if ($go == null) {
        $.cookie("adServingKeywords", "travel")
    }     
</script>

<umbraco:Macro adspaceid="56" keywords="[%adServingKeywords]" Alias="adServing.Wallpaper" runat="server" />