Sorry for the confusion. This is indeed a confusing transition and we're working quickly to get our docs updated to reflect the new way of handling web services in ASP.NET AJAX.
In short, the RadControls for ASP.NET AJAX now rely on ASP.NET AJAX's superior support for web services to provide the functionality Telerik's RadAjaxServiceManager provided. In ASP.NET AJAX, you can use the ScriptManager control to create client-side proxies to your web services. For more details on how this works, check out this tutorial:
Let me know if you have any trouble with the new approach and I'll be happy to help.