Ajax CDN Launched

ASP.NET team launched a new Microsoft AJAX CDN (Content Delivery Network) service, to provide caching support for AJAX libraries (including jQuery and ASP.NET AJAX), for FREE.
This service doesn't require any registration and can be used for both commercial and non-commercial purposes.

CDNs are composed of "edge cache" servers, which are placed around the world at key internet network points. These servers can be used to deliver and cache all types of content, including images, CSS, JS files and videos.
CDNs improves a website's end-user performance drastically, as it enables browsers to more quickly retrieve and download content, to make your pages load faster.

Microsoft AJAX CDN provides a easy way to add the jQuery and ASP.NET AJAX script libraries to serve automatically from one of the thousands geo-located edge-cache servers.

How to use?
ASP.NET 4.0 makes easy to use the CDN from ASP.NET web forms applications that use server control. This control includes a new boolean property named EnableCdn. Change the value to TRUE to request JS files automatically. When CDN is enabled in application it will retrieve all JS files that it normally retrieves from System.Web.dll or System.Web.Extensions.dll assemblies from the CDN instead.

You can get a full listing of JS libraries & URLs @ ASP.NET AJAX CDN