A Google developer, formerly on the Android team, provides a detailed, fair, and clear explanation of how iPhone OS 4 multitasking will work. Robert Love explains the difference between true background application multitasking and Apple's limited set of APIs that let certain processes continue to operate in the background. He also differentiates serialization (quitting an app while preserving its state precisely) and true background operations. follow link
Sleep (and Lock) Your Screen
When you are walking away from your computer, it's fairly common practice to start your screen saver and lock your screen. But did you know that there is a built-in keyboard shortcut in Mac OS X to sleep the screen?
Press Control-Shift-Eject and your monitor sleeps without engaging the screen saver.
- ExtraBITS for 12 April 2010 (12 Apr 10)
Google Developer Explains iPhone OS 4 Multitasking