I just found the most important feature about the new iphone / ipad / ipod touch os 4. It’s called ‘portrait orientaion lock’.
This post will show you how to stop your iphone or ipad screen from rotating or flipping when you turn your device on its side

You can now use your iphone / ipad without it flipping the screen!!!!!
Edit: check here for a post about how to use your ipads side switch for portrait orientation lock