ASP.NET AJAX Architect, Nikhil Kothari, has released 3 updated server controls (one existing, two new) for ASP.NET AJAX 1.0:

UpdateHistory

A non-visual control that allows you to add history entries to the browser's navigation stack selectively for some post-backs, and not for some others. This helps fix the back button to make it work, and allows you to implement Ajax patterns such as "logical navigation" and unique URLs.

 
StyledUpdatePanel

A simple derived UpdatePanel that adds CSS class semantics. A simple addition, but a useful feature, nevertheless, that didn't make the feature cut.

 
AnimatedUpdatePanel

Another derived UpdatePanel that displays new content using a variety of animations or effects: slides, wipes, cross-fades as well as a visual highlight. This allows you to implement the "visual notification" Ajax patterns such as the one second spotlight and one second mutation.

In addition to samples, Nikhil also includes a "WPF/E"-hosted video in his post showing all 3 controls in action so you OS X users can enjoy it too.