I worked on a project while ago that required the use of iFrames to create “AJAX” file uploads.  It took me a little while but I finally worked out how to get the contents of an iFrame using jQuery.  To get the contents of an iFrame we need to wait until the iFramed content has finished loading as well.

var iFrameBody = '';
$('#iframe').load(function(){
    iFrameBody = $(this).contents().find('body');
});