With the latest release of Microsoft AJAX, Beta 1 - things have drastically changed requiring a more stricter model which forces controls to register themselves through the ScriptManager versus using Page.ClientScript. This change, unfortunately, breaks just about every control out on the market when being used within the UpdatePanel control (including ASP.NET controls). Changes need to be made to Excentrics World Server Controls to enable full compatibility, and these changes are under-way. More information will be distributed concerning the new compatibility layer being developed as it is completed and released. Until then, if you require the use of UpdatePanel and Excentrics World Server Controls, I would recommend staying on the July CTP.