To really build good Metro Style Apps, you should download locally the documentation from the Visual Studio 11 BETA. Things are very well explained and documented. Because you can’t rely only on September 2011 BUILD conference presentations, this documentation is a required and you should read it because building a Metro Style Apps is different from building a Windows desktop applications, even if you are a .NET, SL or WPF developer. XAML and WinRT differ in a lot of ways. The learning curve is not really difficult but it takes some times.
Windows 8 Metro Style Apps learning and knownledge