[jQuery] updating content (adding new items)

[introvert]

Hello.

I have a simple twitter shoutbox on my website that I would like to
refresh with jquery each X seconds.

At the moment I use the following code which will hide the block, load
new and show it:

function getTweets() {
$("#twitts").fadeOut("fast");
$("#twitts").load("last-10-twitts.php", '', callback);
}

function callback() {
$("#twitts").fadeIn("fast");
setTimeout("getTweets();", 15000);
}

$(document).ready(getTweets);

I'm looking for more advanced method that will only add new items at
the beginning of the list.
How is it possible to implement that?

Is there any tutorial/example online?

Many thanks in advance.