I have a LayoutDialog with a nested layout panel that worked in alpha3 and does not work in beta1 or beta2. In the betas the north and south panels are not displayed. Here's the code (remove either the includes of alpha3 or beta2 to see it work or not work). (I'm running on FF.)
Thanks.
Code:
<HTML>
<head>

<link rel="stylesheet" type="text/css" href="ext/resources/css/ext-all.css" />

<script src="ext-1.0-alpha3/yui-utilities.js"></script>
<script src="ext-1.0-alpha3/ext-yui-adapter.js"></script>
<script src="ext-1.0-alpha3/ext-all.js"></script>

<script src="ext-1.0-beta2/adapter/yui/yui-utilities.js"></script>
<script src="ext-1.0-beta2/adapter/yui/ext-yui-adapter.js"></script>
<script src="ext-1.0-beta2/ext-all.js"></script>

<script type='text/javascript'>

Ext.onReady(winMain);
function winMain()
{
	var dlg = new Ext.LayoutDialog(
		'ew-dlg', {height:450, width:730, north:{}, south:{}, center:{}});
 	dlg.addButton("OK", function() {alert('ok')});

	var layout = dlg.getLayout();
	var innerLayout = new Ext.BorderLayout(
		'ew-center', { west: {split:true, initialSize:'50%'}, center: {} });
	layout.beginUpdate();
	layout.add('north', new Ext.ContentPanel('ew-north'));
	layout.add('south', new Ext.ContentPanel('ew-south'));
	innerLayout.add('west', new Ext.ContentPanel('ew-center-west'));
	innerLayout.add('center', new Ext.ContentPanel('ew-center-center'));
	layout.add('center', new Ext.NestedLayoutPanel(innerLayout));
	layout.endUpdate();
	
	dlg.show();
}

</script>
</head>
<body>

<div id='ew-dlg' style='visibility:hidden'>
<div class='x-dlg-hd'>LayoutDialog</div>

<div class='x-dlg-bd'>
<div id='ew-north'><button>Button</button></div>
<div id='ew-center'></div>
<div id='ew-center-center'></div>
<div id='ew-center-west'></div>
<div id='ew-south'><button>Button</button></div>
</div>

<div class='x-dlg-ft'></div>
</div>

</body>
</html>