Warning: this is way out of date.
Ember.js is incorporating more UI abilities natively every day, but for now there’s a lot of functionality provided by jQueryUI that is nice to take advantage of. In order to convert the result of a jQuery selector or other array-like jQuery object, use the following:
properEmberArray = Ember.A($.makeArray(jQueryArrayLike));
Sorry if this is obvious, but it gave me some grief before I realized that I was calling map on a jQuery object and not a fully fledged Ember Array.