Asynchronous callbacks for web applications.

One of the issues that web developers are often faced with these days is dynamic behaviour on web pages. Often, falling back on Javascript is the only viable option. However, this article explains how you can support asynchronous client script callbacks that execute code-behind code without the user noticing any activity. ASP.NET 2.0 seems to support this out-of-the box. Look at the Google beta site to get a demonstration (although I doubt it is created in ASP.NET).