This is, of course, the project that our newest Valued Associate, Sam Saffron, has been working so hard on over the last 6-8 weeks.
The project is hosted at Google Code in a Mercurial repository:
The SEDE is built using the very same software stack we use on Stack Overflow:
.NET 4.0 C#
Visual Studio 2010
You can get started using the completely free Visual Studio 2010 Express Edition.
It was always our hope that the SEDE could be used as a freely embeddable web tool to teach SQL with a sample dataset — and now, the code itself is available to modify, improve, and learn from as well.