この単純なプラグインを使用できます: http://css-tricks.com/snippets/jquery/shuffle-dom-elements/
(function($){
$.fn.shuffle = function() {
var allElems = this.get(),
getRandom = function(max) {
return Math.floor(Math.random() * max);
},
shuffled = $.map(allElems, function(){
var random = getRandom(allElems.length),
randEl = $(allElems[random]).clone(true)[0];
allElems.splice(random, 1);
return randEl;
});
this.each(function(i){
$(this).replaceWith($(shuffled[i]));
});
return $(shuffled);
};
})(jQuery);
あなたの場合、次のように使用します:
$('#abc > div').shuffle();