Data Unbound

Here's some code I figured out for doing so that I believe should work:

var tabBrowser = getTabBrowser(chromeWindow);
var tabs = tabBrowser.mTabBox._tabs.childNodes;

for (var i=0; i <tabs.length; i++) {
  var browser = tabBrowser.getBrowserForTab(tabs[i]);
  output(browser.contentWindow.location);
}

It took me a while to gather the pieces, and I'll have to explain how I did it — but for now, let me just note the code here.