This code makes separate radio button groups behave as a single radio group.

jquery.radiogroup.html

<form>
	<p class="radiogroup">
		<!-- This is one radio group -->
		<input type="radio" name="group1" value="1" /> Item 1<br />
		<input type="radio" name="group1" value="2" /> Item 2<br />
		<input type="radio" name="group1" value="3" /> Item 3<br />
 
		<!-- This is a separate radio group -->
		<input type="radio" name="group2" value="1" /> Item 4<br />
		<input type="radio" name="group2" value="2" /> Item 5<br />
		<input type="radio" name="group2" value="3" /> Item 6
	</p>
</form>

jquery.radiogroup.js

// Turn multiple radio groups into one
$('form').delegate('.radiogroup :radio', 'click', function() {
	$parent = $(this).closest('.radiogroup');
 
	$(':radio', $parent).attr('checked', false);
	$(this).attr('checked', true);
});

This code makes separate radio button groups behave as a single radio group.