That's right!  Matt Gibbs and Bertrand Le Roy have just published an O'Reilly Shortcut all about the UpdatePanel.  It is one of the key improvements that "Atlas" brings to ASP.NET developers to make it super simple to AJAX enable your site.  You can buy it for $9.99 here

Let us know what you think, read the description below:

This PDF will teach you how to build richer and more interactive AJAX-style web applications using ASP.NET "Atlas," Microsoft's framework that extends ASP.NET 2.0. "Atlas" provides server controls that make it easy to perform asynchronous partial page updates. The key to making ASP.NET applications more responsive to user input is the UpdatePanel control. In this tutorial, you'll learn from the experts: Bertrand Le Roy, UpdatePanel control's architect and developer, and Matt Gibbs, Atlas dev team manager.

This document shows how the "Atlas" UpdatePanel control can improve the interactivity of an ASP.NET Wizard control. You'll also learn about a master/details page for the AdventureWorks database and a search page with a details preview for the same database. Finally, you'll learn how to display errors associated with UpdatePanel updates and how to deal with a number of its peculiarities. This PDF document is exactly what you need to get started implementing AJAX functionality in existing ASP.NET applications.