I wasn't born yesterday, so I know what people have hiding in the depths of their iPhones. And especially now with the hot new camera on the iPhone 3GS, it's even more tempting to put your iPhone's camera to good use.
If you have risque photos of yourself or others on your iPhone, this is one of those safety precaution apps. Maybe mom wants to take your phone for a test drive and all of a sudden starts browsin' your pics — oops! That's when you wish you woulda had Private Pics installed.