You can now download the July Community Tech Preview of Atlas here. Some Details:

UpdatePanel and ScriptManager:

• ScriptManager.RegisterControl() takes optional parameter to specify client type to create.
• Fix for UpdatePanels in Firefox.

Drag and Drop:

• Added public dragStart/dragEnd events to DragDropManager.
• dragStart fires with dragMode, dataType, and data as eventArgs.
• dragStop fires with empty eventArgs.
• style.position of dragVisuals will no longer default to “absolute”.
• DragDropManager do longers disposes dropTargets when unregistering them.
• FloatingBehavior now unregisters itself on dispose.