Uncheck all JQuery radio buttonset at once
You can match all the radio buttons and use prop() to uncheck them.
However, you also have to refresh the buttonset widget after doing so:
$("#radio").find("input:radio").prop("checked", false).end()
.buttonset("refresh");
You can uncheck them them with the following (updated for jQuery UI 1.9:
$('#radio input').removeAttr('checked');
// Refresh the jQuery UI buttonset.
$( "#radio" ).buttonset('refresh');
Working JSFiddle.