jquery sortable placeholder height problem
I usually solve this by binding a callback that sets the height of the placeholder to the height of the item being sorted to the start event. It's a simple solution that gives you fine-grained control over how you want your placeholder to be displayed.
$( ".column" ).sortable({ connectWith: ".column", start: function(e, ui){ ui.placeholder.height(ui.item.height()); }});
Have you tried setting the forcePlaceholderSize:true property? Have a read on the jQuery UI Sortable documentation page.
Are your elements display: block ? Inline elements might make the placeholder not keep the height correctly. Eg. this jsFiddle seems to have a similar problem to the one you described. Adding display: block to the .portlet class fixes it.