Getting the last row of a table using jQuery?

var id = $('table tr:last').attr('id');

Old question, but here's a different way using JQuery traversal which is a bit quicker:

$("#TableId").find("tr").last();

An alternative method to ID your rows, if they are all sequential is just to get the number of rows + 1.

$("#TableId").find("tr").length + 1

$('#yourtableid tr:last').attr('id');