The initial beta is available to developers in the iOS Dev Center. iOS 4.3 for the iPhone, iPad and iPod touch is dubbed build 8F5148b.
According to Macstories.net, iOS 4.3 brings new multi-touch gestures built specifically for the iPad, including 4- and 5-finger gestures. The new beta reportedly allows users to pinch to access the home screen, to swipe up to reveal the multitasking tray, and swipe left and right to switch between open applications.
In addition, another iOS 4.3 beta for the Apple TV was also released. It allows developers to test AirPlay functionality with iOS applications on the new Apple TV.
Update: In addition, the new update also reportedly adds the ability to change the functionality of the iPad hardware switch. When the iPad launched, the switch originally acted as an orientation lock, but with the release of iOS 4.2, the button changed to mute the device.
The download page makes no mention of the iPhone 3G or second-generation iPod touch. Supported devices are the iPad, iPhone 4, iPhone 3GS, third-generation iPod touch, and fourth-generation iPod touch.
The new beta confirms rumors that Apple would add its new Personal Hotspot feature to existing GSM iPhones with iOS 4.3. The functionality allows users to share their 3G data connection with up to five devices over Wi-Fi. Those reports claimed that Apple plans to publicly release iOS 4.3 in March.
The new Wi-Fi tethering ability was first revealed on the new CDMA iPhone for Verizon when the product was announced on Tuesday. That forthcoming phone was demonstrated running a different version of iOS, 4.2.5. The latest public version of iOS for the iPhone, iPad and iPod touch is 4.2.1.