You can use the items
option of jQuery UI's sortable for this purpose.
The idea would be that you place a class on the items that you actually want to be sortable and then use the items
option to select them.
This class could be from a computed. The computed in your case could potentially be related to the last item in the list.
When you bind, it would look like: sortable: { data: items, options: { items: '.good-items' } }
Here is a basic sample: http://jsfiddle.net/rniemeyer/mBjHN/