Using jQuery to re-order and animate list items?

So, I've got a list of items, something like:

<ul id="listHolder">
    <li id="l1">List item 1</li>
    <li id="l2">List item 2</li>
    <li id="l3">List item 3</li>

etc. An ajax call is being fired periodically, and I may need to re-order the list (by making one of the lower items become the first one in the list). That's easy to do just by changing the HTML of #listHolder, but I would like to animate it so the appropriate item moves up the page to the right place, and the others move down.

I've got no idea where to start =/

NB. It doesn't have to be a list: a div or any other element would be fine.