Windows Explorer: How to create additional button?

Question

Hello

Explorer of Windows 7 uses a new light-blue bar with buttons like "Organize", "Share", "New Folder" etc.

How can I create a new button ? Do I need to create a plugin for explorer.exe, and if, how do I do it (using Visual Studio .NET) ?

Or is it a simple registry key I have to set which points to an exe or bat?

Thanks in advance and best regards