iPhone OS 3.1 has been announced today in Apple Rock and Roll event. Here’s a list of all the features which are included in the upgrade:

• Video editing on iPhone 3GS wont overwrite the clip over the original when you are editing a clip.
• A new option for checking tethering data statistics.
• iPhone will now vibrate whenever you switch to the mode where you can move and arrange icons on the iPhone home screen.
• Improvements in the performance of Compass on iPhone 3GS.
• Directional orientation in Google Maps app is now more accurate.
• Copy/Paste support for address book and numeric keypad in Phone application.
• “Fraud Protection” toggle has been added to settings under Safari.
• iPhone boot time is now faster.
• Voice Control over Bluetooth.
• Password-locked phones will now ask for a PIN, the first time the device is plugged into a new computer for syncing.
• New APIs to enable third party apps to access videos and edit them.
• Developers can now work with an iPhone wirelessly (WIFI) instead of having to connect it to their development computer via USB.
• Non-destructive video button names changed to Trim Original and Save as New Clip, this should help clear up the confusion caused by the original names Save and Save a Copy.
• New enhancements to Core Audio has been added.
• Support for copy/paste of videos into email.
• Support for Instruments (on your Leopard or Snow Leopard OS X machine) over Wi-Fi instead of USB for developers to test benchmarks in apps for memory leaks, performance etc.
• Video attachments can now be saved into photo album.
• Improved battery life.
• Failover support for HTTP live streaming.
• Support for VM Tracker in Snow Leopard.
• Improvements to OpenGL and Quartz.
• MMS support for AT&T customers.
• Official API support for Augmented Reality apps. (unconfirmed)
• More accuracy in battery % meter. (unconfirmed)
• A toggle for Batter % for all devices. (unconfirmed)
• Password protection toggle for “Find my iPhone”. (unconfirmed)
• Real-time zoom for camera

• Numerous other bug fixes.

You can upgrade your iPhone OS to 3.1 from the iTunes.