Well, it’s not. As The Register reports, “press of the “Emergency Call” key from the passcode entry screen, followed by a double-tap on the home button. That takes the miscreant into favourites, from which they can access the address book, from which they can get into the e-mail client (by tapping a contact’s e-mail address) or the browser (by tapping a URL).”
I’d expect better protection on a device that can carry sensitive personal information, such as contacts, e-mail and more. Note that the iPod touch is better protected, since there is no emergency call key; the only option you have from the passcode screen is to enter the passcode.
UPDATE: More info and details here.
