None of the previous suggestions worked for me in jQuery 1.7.2 because I'm trying to set the selected index of the list based on the value from a textbox, and some text values are contained in multiple options. I ended up using the following:
$('#mySelect option:contains(' + value + ')').each(function(){
if ($(this).text() == value) {
$(this).attr('selected', 'selected');
return false;
}
return true;
});