下部には、jsfiddle と例があります。お役に立てれば。
$(document).ready(function(){
$(".droppable").droppable({
drop: function(event, ui) {
var $list = $(this);
$helper = ui.helper;
$($helper).removeClass("selected");
var $selected = $(".selected");
if($selected.length > 1){
moveSelected($list,$selected);
}else{
moveItem(ui.draggable,$list);
}
}, tolerance: "touch"
});
$(".draggable").draggable({
revert: "invalid",
helper: "clone",
cursor: "move",
drag: function(event,ui){
var $helper = ui.helper;
$($helper).removeClass("selected");
var $selected = $(".selected");
if($selected.length > 1){
$($helper).html($selected.length + " items");
}
}
});
function moveSelected($list,$selected){
$($selected).each(function(){
$(this).fadeOut(function(){
$(this).appendTo($list).removeClass("selected").fadeIn();
});
});
}
function moveItem( $item,$list ) {
$item.fadeOut(function() {
$item.find(".item").remove();
$item.appendTo( $list ).fadeIn();
});
}
$(".item").click(function(){
$(this).toggleClass("selected");
});
});
http://jsfiddle.net/caferdo/k5XJv/3/