Here is an ASP.NET webcast I recorded that provides a technical overview of Atlas. This webcast covers the areas below with a number of demos and I answer questions from the webcast attendees. Update: You can now download the .wmv file for offline viewing.

ASP.NET Atlas server programming model covering atlas:ScriptManager, atlas:UpdatePanel, AutoComplete Control Extender 

ASP.NET Atlas client programming model covering calling web services, components and bindings, datasources, listview control, behaviors, drag and drop, profile.

Here is the link for Nikhil's Web Development Helper for networking tracing and DOM inspection.

Update: you can download the samples at: http://go.microsoft.com/fwlink/?LinkId=62605

enjoy!
-jhawk