+1 to getting oauth implemented to support access tokens. You guys give the illusion that it is working in the External App Auth tester page, but it doesn't seem to actually work outside of that page. At least now we know!
To those playing, yes, you can get going with the .NET library, although you either (1) have to hard code the user id or (2) manually use the External App Auth to get an access token, copy it into your app, and then call http://api.myspace.com/v1/user to get the user id.