Locking iPhone Screen Rotation
iPhone’s automatic screen rotation is convenient. However, it is annoying under some situation, such as reading email in the bed. Fortunately, iOS 4/iOS 5 have an option to lock the screen rotation. But it is a little tricky to find it out.
This option is hidden in the multitasking bar. Yes. It’s there. Double click the home button, swipe right till the most left screen and the icon to lock screen rotation is on the most left.
A screenshot on iPhone (which worth a thousands words):