There’s a new video of a Longhorn-based real estate application up on MSDN.  I’ve got to say this is one of the coolest things I’ve seen in a long while.  The new Avalon execution model allows you to do some truly amazing things with Smart Client applications.  These same techniques could be applied to stock tracking, or any other kind of notification based application.  Just send out an email with a notification, and an attached Smart Client for more info.  What a great idea.