In what appears to be a last minute hardware change, Apple has replaced what was formerly the “mute” switch on the iPad with a “screen rotation lock” switch. Pictured above on the left is how the iPad formerly appeared on Apple’s website, and pictured above on the right is how it appears now.
MacRumors writes why the change is necessary:
Like the iPhone, the iPad automatically senses its orientation and adjusts its display between portrait and landscape modes with no user input required beyond turning the device. One common complaint among iPhone users has been, however, that there is no system-wide mechanism to lock the screen in one orientation. The lack of screen rotation lock on the iPhone is particularly frustrating to those attempting to use their devices while lying down on their sides and finding their iPhone rotating the display to an “upright” position.