NOTE! The presorting of an empty table and automatic sorting of appended data was added in version 2.0.14 (not part of the original plugin).

Demo

First Name
Last Name
Age
Total
Discount
Date
Append new table data

Javascript

$(function() {

// Set up empty table with second and first columns pre-sorted
$("table").tablesorter({ theme : 'blue', sortList: [[2,1],[0,0]] });

$("#append").click(function() {

// add some html
var html = "<tr><td>Peter</td><td>Parker</td><td>28</td><td>$9.99</td><td>20%</td><td>Jul 6, 2006 8:14 AM</td></tr>" +
"<tr><td>John</td><td>Hood</td><td>33</td><td>$19.99</td><td>25%</td><td>Dec 10, 2002 5:14 AM</td></tr><tr><td>Clark</td>" +
"<td>Kent</td><td>18</td><td>$15.89</td><td>44%</td><td>Jan 12, 2003 11:14 AM</td></tr>" +
"<tr><td>Bruce</td><td>Almighty</td><td>45</td><td>$153.19</td><td>44%</td><td>Jan 18, 2001 9:12 AM</td></tr>";

// append new html to table body
$("table tbody").append(html);

// let the plugin know that we made a update, then the plugin will
// automatically sort the table based on the header settings
$("table").trigger("update");

return false;
});

});

HTML

<table class="tablesorter">
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
<th>Total</th>
<th>Discount</th>
<th>Date</th>
</tr>
</thead>
<tbody>
</tbody>
</table>

<a href="#" id="append">Append new table data</a>