Today Apple released the final build of iOS 4.3 for the iPad, iPad 2, iPhone 3GS, iPhone 4 (GSM only), iPod Touch 3G and 4G. The first Beta for iOS 4.3 was released on the 12th of January, second released on January 19th and the third and final one was released on 1st February. The GM was released on 2nd March.

iOS 4.3 brings a lot of changes including the following:

The ability to cancel the download/install of an app.Personal hotspot options for the iPhone 4 (GSM only) which are limited to the carrier.Airplay for third part apps.Multi-touch gestures for the iPad 1 and 2 which are currently developer only.Choosing between the mute and switch and rotation lock for the iPad's side switch button.Nitro JavaScript engine from the desktop version of Safari which improves iOS' Safari's performance a lot.Subscription based payments for the App Store.Facetime and Photo Booth for the iPad 2.iTunes' home sharing features and a lot of other performance and stability upgrades.

You can install the iOS 4.3 directly from iTunes or use the following links, Just download the files and open them in iTunes. Click the install button when the file opens in iTunes if promted.

iPhone 4 (GSM only)iPhone 3GSiPadiPad 2iPod Touch 4GiPod Touch 3GApple TV 4.2

Source: Apple