Apple has announced iPhone OS 3.1 at Rock and Roll event. The new iPhone OS is just released after three months of iPhone OS 3.0. The iPhones and iPods which are running on iPhone OS 3.0 can get upgrade to iPhone OS 3.1 absolutely for free.

The iPhone OS 3.1 features and updates are as follows:

• Genius Recommendations for Apps
• Genius Mixes
• Download Ringtones Wirelessly
• Organize Apps in iTunes
• Improved syncing for music, movies, TV shows, podcasts, and photos1
• iTunes U content organization1
• Redeem iTunes Gift Cards, codes, and certificates in the App Store
• Display available iTunes account credits in the App Store and iTunes Store
• Save video from Mail and MMS into Camera Roll
• Option to “Save as new clip” when trimming a video on iPhone 3GS
• Better iPhone 3G Wi-Fi performance when Bluetooth is turned on
• Remotely lock iPhone with a passcode via MobileMe
• Use Voice Control on iPhone 3GS with Bluetooth headsets
• Paste phone numbers into the keypad
• Option to use Home button to turn on accessibility features on iPhone 3GS
• Warn when visiting fraudulent websites in Safari (anti-phishing)
• Improved Exchange calendar syncing and invitation handling
• Fixes issue that cause some app icons to display incorrectly

Furthermore, iPhone OS 3.1 also includes the features of iPhone OS 3.0.

Download iPhone OS 3.1