iOS 4.3 was initially scheduled to launch on Friday, alongside the iPad 2, as per an official announcement from Apple last week. But Apple decided to pull the trigger two days early, and less than a week after the golden master was issued to developers.
Another major feature is Personal Hotspot, which allows iPhone 4 users to share their 3G data connection over Wi-Fi. Personal Hotspot will work with supporting carriers -- including AT&T -- with the appropriate monthly data plan.
The Personal Hotspot feature was first introduced on the Verizon CDMA iPhone 4 introduced in February. But while Verizon users had early access to Personal Hotspot, those customers will have to wait for iOS 4.3, as the CDMA iPhone 4 has a different baseband chip than its GSM counterpart.
iOS 4.3 also features improved iTunes Home Sharing, which allows users to access all of their content directly over Wi-Fi. With Home Sharing, music and movies can be streamed from a Mac or PC to an iOS device over a local home wireless network.
And iOS 4.3 also adds the ability for third-party applications to support AirPlay, Apple's wireless streaming standard. Applications that add the feature will be able to stream both audio and video to the new Apple TV, or audio to an AirPort Express. In addition, sharing of photos over AirPlay can use the built-in slide show options of iOS, and videos recorded on an iOS device can be streamed to the Apple TV.
With iOS 4.3, users can change the purpose of the hardware switch on the right side of the iPad and iPad 2. The switch can now mute audio from the device, or it can serve as an orientation lock, as it originally did when the iPad first shipped last year.
The iOS 4.3 update is compatible with the iPhone 4, iPhone 3GS, first-generation iPad, iPad 2, and the third- and fourth-generation iPod touch. Users will need iTunes 10.2.1, released by Apple on Tuesday, to sync and update their mobile device.