Does Force-Directed Layout of d3-js support image as node?

Question

d3 has a demo of a Force-Directed Graph Layout.

Instead of circles, I want all nodes in the graph to be images.

so, I changed

 .append("svg:circle")
      .attr("class", "node")
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; })
      .attr("r", 5)
      .style("fill", function(d) { return fill(d.group); })
      .call(force.drag);

to

.append("xhtml:img")
   .attr("src", "http://a577.phobos.apple.com/us/r1000/081/Purple/12/61/13/mzi.lgqdzwfu.png")
   .call(force.drag);

But I can not see any images. What am I doing wrong?