#map 元素必须在页面中可见...

The #map element must be visible in the page...

所以需要把初始化代码放在slideToggle的回调中.

So you need to put the initialization code in the callback to the slideToggle.

$(document).ready(function() {

    //Hide (Collapse) the toggle containers on load
    $(".toggle_container").hide();

    //Switch the "Open" and "Close" state per click then slide up/down (depending on open/close state)
    $("h9.trigger").click(function() {
        $(this).toggleClass("active").next().slideToggle("slow", function() {
            if ($(this).is(':visible')) {
                map = InitMap(null, 'map', centerCoord, true); // initialize the map on default location
            }
        });
        return false; //Prevent the browser jump to the link anchor
    });

    handle_clicks(); // click events handling by jQuery    
});

演示在 http://jsfiddle.net/gaby/A5jnV/