If you mean GameFest instead of XFest (which, as I understand it, is now dead) then I'm not aware of a public download for any source code.
You could always email directx@microsoft.com to see if they're prepared to let you have it. But, based on them stripping some videos out of the GameFest slides, I'd imagine you'd had to of been there to get any additional material...
hth
Jack
Hmm...it may be that the source IS indeed available. I'll ask Shanon about it today and follow up here (it's possible that I made a mistake *gasp!* and didn't post it online
)
Shanon just pointed out that the code samples he uses are the same D3D 10 samples found in the DirectX SDK, so no "secret sauce" involved. Just download the SDK and you're all set!