According to the Internet, we should all set the date on your iPhone, iPad, or iPod touch to 1970, and then restart it to watch it brick (Don't do this. It'll probably brick your device, and you'll have to explain to the Genius Bar why you did thought that was a good idea.). Apple says it's a real problem, and a fix is on the way.
Don't try the iPhone 1970 date thing, just trust that Apple is fixing it.
The bug crops up when you set the date on your iOS device to May 1970 or earlier, and then restart. Odds are your iOS device won't turn on any more, turning it into a high tech paper weight.
Sure, you can do it, but there isn't any reason why you should unless you're a time traveler. Even if you are, your iPhone would be little more than an iPod since the wireless technologies we rely on to get on the Internet or even make phone calls wouldn't exist yet. Also, you could completely disrupt the timeline by accidentally introducing iPhone-level technology decades too early.
Why would setting the date on your iPhone to 1970 kill it, you ask? The exact reason is something Apple is sorting out right now, but we do know where it starts.
iOS is a Unix-based operating system, and Unix counts time from a predefined start date: the Unix Epoch. That date happens to be January 1, 1970, and every Unix-based device has been counting seconds from that point forward.
Knowing that, you'd assume you can't set the date on your iPhone, iPad, or iPod touch earlier than the Unix Epoch, and you'd be right. The problem, then, is probably related to how something in iOS handles dates, and when you get too close to the zero point—in this case, earlier than May 1970—something goes horribly wrong and you device won't boot up any more.
The easy way to avoid the problem is to not set your iOS device's date that far back in time. You don't really need to see your iPhone brick to know the date bug works; just trust us on this one.