We recommend everyone to start using RadControls for ASP.NET AJAX Q1 2008 (formerly "Prometheus") - the dll version is 2008.1.415.The suite is now officially released and is no longer in beta.
As of our current release this is the prime offering of web controls from Telerik.
For more details please refer to this page:
Let me know if you have any further questions.
the Telerik team