This is not a valid script token
<script src="http://jquery-ui.googlecode.com/svn/tags/1.8.22/"></script>
It needs to point at the js file, something like
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js" type="text/javascript"></script>
Your full source should read like so...
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SPA.aspx.cs" Inherits="SPA" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div class='liveExample'>
<p>
First name:
<input data-bind='value: firstName' />
</p>
<p>
Last name:
<input data-bind='value: lastName' />
</p>
<h2>Hello, <span data-bind='text: fullName'></span>!</h2>
</div>
</form>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js" type="text/javascript"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js" type="text/javascript"></script>
<script src="http://ajax.aspnetcdn.com/ajax/knockout/knockout-2.1.0.js"></script>
<script>
var ViewModel = function (first, last) {
this.firstName = ko.observable(first);
this.lastName = ko.observable(last);
this.fullName = ko.computed(function () {
return this.firstName() + " " + this.lastName();
}, this);
};
$(document).ready(function () {
ko.applyBindings(new ViewModel("Planet", "Earth"));
});
</script>
</body>
</html>