I wan\'t to customize the icon displayed within the windows 7 taskbar. When my app is running, I can do it by changing main window icon but, when the app is pinned, the exe\
When you pin an application to the TaskBar, it simply creates a shortcut in the following directory:
C:\Users\\AppData\Roaming\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar
You should be able to identify where the shortcut is (ie, get KnownFolders and work from there. UserAppData should be the one), and then using P/Invoke (IShellLink), you can alter the icon that the shortcut is setup to use. The machine might need a reboot for this to take effect, but it should work.
If you hold down Shift while right-clicking on the pinned application, and select Properties, you can see the Change Icon button for the shortcut. This is basically what you need to emulate with code.
All of these things can definately be done with code, but whether you think they're any better than the registry setting is up to you.