Up until several months ago I was a huge proponent of FBML. Why do FQL queries when you dont have to? Why deal with doing all the CSS? Why deal with resizing (which was giving us alot of issues)? Doing an iFrame method just seemed like an excessively heavy way of doing things, and at that time I think FBML was the right way to do it.

What changed? At Facebook the resizing script stabilized, the JS API client library was introduced, and with connect increased support for iFrames arrived. Plus at Slide there was an increased emphasis on quality, not just quick iteration. With these changes, FBML became the “WYSIWYG” way of doing things vs iFrame being the “advanced” way. As the applications are Now with iFrame we can load faster as we dont have to do round trips from Facebook in order to process the data, rather the browser can hit our servers direct.