Andrej Tozon published the next two articles of the "Countdown to Silverlight 3" series. Here they are: Part 4: Element binding and Part 5: ChildWindow (Modal, Non-modal, Templated). You can find links to the previous three posts here.
There are many controls being introduced in Silverlight 3; a lot of them were pulled from the Silverlight Toolkit (the idea is that for every new Silverlight version, Toolkit controls marked as stable are moved to the Silverlight core. I’m not sure how many new controls I’m going to cover in this series, but the ChildWindow definitely deserves a separate post and sample.