Many people have been complaining about the WP7’s shutter sound and how it cannot be disabled. It even sounds when your phone is in silent mode. Fortunately, there is a solution it.
For this you will have to have an unlocked windows phone 7 device and registry editor installed. Follow my Windows Phone unlocking guide and then install registry editor for WP7. After that, fire up registry editor and go to:
Change the value of “BypassDeviceGain”=dword:0