Well, the mute switch now works just like the iPhone - which is dumb IMO because the iPhone "rings" and the iPad can't.
Really all you do is turn off notifications, but games and music will still continue to play under "mute".
If you still haven't found it, the rotation lock "switch" is displayed when you double-tap the home button and scroll all the way to the left in the task bar.
Its there to meet cetain legal requirements i think .... all mobile devices have comply with rules and regulations that mean it must be able to mute all sound