June 21st Update: Here is a pointer to even more content.
http://atlas.asp.net is the best place to visit to learn more and download the latest Atlas CTP Release (which now supports Go-Live deployments).
If you haven't had a chance to dive into Atlas yet, you might want to set aside 18 minutes to watch this "How do I" video on the Atlas home-page that walks through how to build a Todo Task List using Atlas from scratch (I type everything in from scratch - including creating the database, building a DAL layer using typed tableadapters, then creating a filtered, sortable, pagable, inline editable task list UI w/ Ajax updates). It shows off the power of ASP.NET 2.0 and Atlas in building smooth, user-friendly, web experiences -- as well as how easy it is.
I also have an intro to Atlas presentation w/ samples that I posted a few weeks ago here. This provides a really easy way to master the core concepts of Atlas.
Brad Abrams (who is the GPM for the team that builds ASP.NET and Atlas) recently published his slides+samples from his Atlas talk at the MIX06 conference, including his cool interactive Atlas Dice application.
You can download Brad's presentation + samples here.
Nikhil (who is a key Atlas architect) also just posted the slides+demos from his MIX talk. He built a cool online music library ("musicMix") that integrates RSS feeds from iTunes, SOAP services with MSN Search, REST services from Amazon, and the new Live Clipboard concept to share information across applications. It is a really awesome sample.
You can download Nikhil's talk + sample here.
Bertrand (who is a key Atlas dev) just posted a cool post about the accordian control he built to help Brad's Dice demo above. You can read about it and download it here.
Jonathan Hawkins (who is a key PM on the Atlas team) recently posted a great tutorial on building a map-mashup using Atlas.
You can read and download the code here.
Shanku Niyogi (who runs the ASP.NET and Atlas teams) has just posted a cool sample showing how to use Atlas with PHP. You can read about it and download it here.
Scott Issacs (who is a Windows Live Architect) just posted his slides from MIX where he shared his "Lessons from the Trenches" talk where he talked about the real world Ajax developer experiences and lessons learned from building Live.com. You can read and download it here.
Hopefully lots of fun stuff to check out and enjoy!
P.S. Shanku is going to post his Atlas slides+demos shortly. He will include a sample that shows how to use Atlas against a PHP backend -- which the MIX crowd really loved.