Win7 progress bar on the application icon in the task bar?

I was wondering how you can turn the application icon in the task bar on windows 7 into a progress bar. I not开发者_高级运维iced some other applications doing this such as IE9, when you download the icon shows the download progress in the task bar.

Can someone tell me how to do this in a .Net 4.0 WPF application?

The number one result from a Google search for "taskbar progress wpf":

Showing Progress in the Windows 7 Taskbar with WPF 4