Nice video!  Since RIA is still relatively new to some of us, these videos help.  However, all the videos and tutorials that I have seen on WCF RIA so far only show editing of simple textboxes in a DataGrid or DataForm.  Almost all REAL WORLD applications require the use of ComboBoxes or some type of drop down to choose from a list of allowed string options.  If you search for this on the web, and there are a LOT of posts, almost everyone runs into a brick wall.  Why is this not in any of the tutorials.  We can't continue to convince management that Silverlight 4 RIA is the right choice when it is so difficult to implement common scenarios.

Thanks, and please schedule a tutorial/video on the use of ComboBoxes in DataForms.