Last week we released the June CTP build of Atlas. You can download it now from the http://atlas.asp.net site.
In addition to bug-fixes, the big new feature provided with this Atlas release is support for dynamically adding UpdatePanel controls within an ASP.NET page. What this means is that you can now embed UpdatePanels within DataLists, within WebParts, within any template of a control, and within other dynamically created composite controls. This greatly expands the places that UpdatePanels can easily be used, and enables a ton of new scenarios.
Control developers can also now use UpdatePanels when building composite controls. Nikhil has a nice post that describes how a control developer can use updatepanels within composite controls to enable Ajax scenarios within portions of a control. You can read his post on how to-do this here.
Three new controls were also added to the Atlas Control Toolkit last week. These include a nice "Accordian" control to enable collapsable multi-regions, a "NumericUpDown" control to easily increment/decrement numeric values, and a "ResizableControl" to enable user resizing of any control element. You can download the source code to these controls and start using them now here. Note that the current download as of this weekend is still using the April CTP of Atlas -- the Atlas Control Toolkit team will be updating the drop to use the June CTP later this week.
For additional information on Atlas also make sure to checkout this recent Atlas resources list I posted here.
Hope this helps,