Very simple :)
<a href="#" id="blob" class="btn large primary" rel="popover">hover for popover</a>
var img = '<img src="https://si0.twimg.com/a/1339639284/images/three_circles/twitter-bird-white-on-blue.png" />';
$("#blob").popover({ title: 'Look! A bird!', content: img, html:true });