folks,
I got this Bootstrap dropdown working. I modified the click event slightly in order to keep the currently-selected image. And as you see, the USD currency is the default selected :
<div class="btn-group" style="margin:10px;"> <!-- CURRENCY, BOOTSTRAP DROPDOWN -->
<!--<a class="btn btn-primary" href="javascript:void(0);">Currency</a>-->
<a class="btn btn-primary dropdown-toggle" data-toggle="dropdown" href="#"><img src="../../Images/flag-usd-small.png"> USD <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="javascript:void(0);">
<img src="../../Images/flag-aud-small.png" /> AUD</a>
</li>
<li><a href="javascript:void(0);">
<img src="../../Images/flag-cad-small.png" /> CAD</a>
</li>
<li><a href="javascript:void(0);">
<img src="../../Images/flag-cny-small.png" /> CNY</a>
</li>
<li><a href="javascript:void(0);">
<img src="../../Images/flag-gbp-small.png" /> GBP</a>
</li>
<li><a href="javascript:void(0);">
<img src="../../Images/flag-usd-small.png" /> USD</a>
</li>
</ul>
</div>
/* BOOTSTRAP DROPDOWN MENU - Update selected item text and image */
$(".dropdown-menu li a").click(function () {
var selText = $(this).text();
var imgSource = $(this).find('img').attr('src');
var img = '<img src="' + imgSource + '"/>';
$(this).parents('.btn-group').find('.dropdown-toggle').html(img + ' ' + selText + ' <span class="caret"></span>');
});