I will also post an bug report at jQuery, but on the odd chance that Google picks this up and you are trying to figure out why a little bit of jQuery is not working in MSIE.
My code that was wrong looked like this:
var zipcode = $("#zipcode").val();
alert(zipcode);
And the alert was empty.
But if I made this small modification
var zipcode = '';
zipcode = $("#zipcode").val();
alert(zipcode);
The alert shows the correct value.
Wierd, huh?