With SpyPhoto you can take a picture in less than 1 second, without making any sound or enabling flash. It is the best option to take pictures without any suspicion.
Just make the gesture that you configure (or double tap Status Bar by default) to take the picture. You don’t even need to be on the camera app, you can take the picture from any app or even lockscreen. You can configure the gesture in Settings.app->SpyPhoto->Activation Methods.
Please enable “Change with Buttons” inside Settings.app->Sounds->Ringer and Alerts
I am not responsible for what people do with this tweak
If it is playing the shutter sound, please go to Preferences.app->Sounds and move the slider. Then try again
Activation method must be set; by default it is ‘hold statusbar’
NOTE FOR IPHONE4 USERS: Taking picture from back camera takes ~4 because of the slow initiation of the camera device