Código HTML:
Ver original <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script> <script type="text/javascript"> $(document).ready(function(){
$('#habilitarRadios').click(function(){
$('.radio').removeAttr("disabled");
});
});
<input type="radio" name="radio" class="radio" value="1" disabled="disabled" /> <input type="radio" name="radio" class="radio" value="2" disabled="disabled" /> <input type="radio" name="radio" class="radio" value="3" disabled="disabled" /> <input type="button" value="Habilitar" id="habilitarRadios" />