OK, this should be super low hanging fruit.
I'm aware of .last() and yet for some reason my copy of jquery-min (version 1.4.2) is returning a .last is not a function() error when I call $('form#demo td').last() on the following markup:
<form id="demo">
<tr>
<td>1</td>
<td>2</td>
<td class="action">3</td>
</tr>
</form>
even though a call to $('form#demo td') returns
[td, td, td.action]
at the firebug console in Firefox 3.5.5.
What am I missing?