function evalHTML(value) {
        if (typeof(value) != 'string') {
                return null;
        }
        value = MochiKit.Format.strip(value);
        if (value.length == 0) {
                return null;
        }

        var parser = MochiKit.DOM.DIV();
        var html = MochiKit.DOM.currentDocument().createDocumentFragment();

        var child;

        parser.innerHTML = value;
        while ((child = parser.firstChild)) {
                html.appendChild(child)
        }
        return html
}

function evalHTMLRequest(req) {
        return evalHTML(req.responseText);
}

evalHTML takes a string and returns a DocumentFragment? object representing the HTML Nodes suitable of inserting via MochiKit or regular DOM, Works in IE, FireFox? and Safari

example:

MochiKit.DOM.appendChildNodes(document.body, evalHTML('<p>Hello World</p>'))

evalHTMLRequest is useful combined with MochiKit.Async.doSimpleXMLHttpRequest to load html fragments or pages

With an html fragment available at http://www.example.com/frag.html can be retrieved easily with the below code

var d = doSimpleXMLHttpRequest("http://www.example.com/frag.html")
d.addCallback(evalHTMLRequest);
d.addCallback(function(html) {
   //do something with the html nodes here
});