Apple has released iOS 4.0 for iPhone and iPod touch through iTunes. The new release can be installed by connecting your iPhone or iPod touch to your computer, selecting it from the left-hand pane in iTunes, then clicking “check for update.”
If you can’t see the update, Make sure you are using iTunes 9.2, which is available through Software Update.
Back up your device in iTunes before applying the update. Some users have reported loss of contacts or other data during the update process.
Problems after the update? Let us know.