Metro style apps are designed to leverage special hardware capabilities and context information to create an experience that is tailored for the user. For example, an app that uses sensors to determine your location, delivering content appropriate to that context, while also using an ambient light sensor to adjust the brightness level of the screen. Metro style apps are built using your existing skills and can reuse code assets you already have. If you know web development technologies, you can use HTML5, CSS3, and JavaScript. Or, you can use more traditional programming techniques.

The following links are useful to learn the Metro Style programing model:

1-    Metro Style App Development Official Website

http://msdn.microsoft.com/en-us/library/windows/apps/

2-    Tools for Metro style app development

http://msdn.microsoft.com/en-us/library/windows/apps/br211374%28v=VS.85%29.aspx

3-    Videos of How to Create Metro Style Apps

http://channel9.msdn.com/Events/Build/Build2011

4-    Samples of Metro Style Apps

http://code.msdn.microsoft.com/windowsapps

From C# Learners

5-    Metro Style Apps

From MSDN

6-    Metro Style Apps – Walkthroughs

http://msdn.microsoft.com/en-us/library/windows/apps/hh464943.aspx

http://msdn.microsoft.com/en-us/library/hh440545%28v=vs.110%29.aspx

From Code Project

7-    Metro Style Apps

http://www.codeproject.com/KB/WPF/WpfMetro.aspx

http://www.codeproject.com/KB/gadgets/MetroPuzzle.aspx

http://www.codeproject.com/KB/WinRT/MetroStyleToggleW8DevPre.aspx

http://www.codeproject.com/KB/WinRT/AddAppBarXAMLMetroApp.aspx

http://www.codeproject.com/KB/ThirdParty-Reviews/metroimageprocessing.aspx

http://www.codeproject.com/Articles/269351/WinRT-Transitions-Creating-Fast-and-Fluid-Metro-UI.aspx

http://www.codeproject.com/Articles/255730/TweetSearch-A-Cross-platform-Metro-UI-WinRT-and-Si.aspx

From C# Corners

8-    Major characteristics of UI of the Metro style apps

http://www.c-sharpcorner.com/Blogs/7148/what-makes-an-app-a-metro-style-app.aspx

From CodePlex

9-    Metro Applications

http://8metro.codeplex.com/

10-   MP2 Metro

http://mp2metro.codeplex.com/

11-   Metro Pandora

HAPPY CODING :)