index.html

<div id="template" style="display:none;">
<tpl for=".">
  <div style="width:250px; float:left; background-color:#777777; margin: 5px;">
    <img src={profile_image_url}  />
    <span>
      <a title="{name}" href="http://twitter.com/#!/{screen_name}"><strong>{screen_name}</strong></a>
      <span>{name}</span>
    </span>
    <div>{description}</div>
  </div>
</tpl>
</div>

<div id="palestrantes"></div>

TwitterListView.js

Ext.XTemplate.from = function(el){
    el = Ext.getDom(el);
    var string = el.value || el.innerHTML;
    string = string.replace(/%7B/g, "{").replace(/%7D/g, "}").replace(/%21/g, "!");
    return new Ext.XTemplate(string);
};

if(!Array.prototype.add) {
    Array.prototype.add = function(item) {
        this[this.length] = item;
        return this;
    };
};

var TwitterReader = new Ext.data.JsonReader({
    idProperty: 'id', root: 'users', totalProperty: 'results',
    fields: [
        {name: 'description', mapping: 'description'},
        {name: 'profile_image_url', mapping: 'profile_image_url'},
        {name: 'name', mapping: 'name'},
        {name: 'screen_name', mapping: 'screen_name'}
    ]
});

var TwitterProxy = new Ext.data.ScriptTagProxy({
  url: 'http://api.twitter.com/1/cmilfont/braziljs/members.json', restful: true
});

var store = new Ext.data.Store({ reader: TwitterReader,  proxy:  TwitterProxy });

Ext.onReady(function(){
    Ext.QuickTips.init();

    data = [];
    store.load({
        callback: function(records, options, sucess) {
            this.each(function(record){
              data.add({
                  name:              record.get("name"),
                  screen_name:       record.get("screen_name"),
                  description:       record.get("description"),
                  profile_image_url: record.get("profile_image_url")
              });
            });
            var tpl = Ext.XTemplate.from("template");
            tpl.compile();
            tpl.append("palestrantes", data);
        }
    });

});