The newest version of Apple's mobile operating system, iOS 4.3, is available as a free download today. Here's a rundown of the new features it offers:

• WIth AirPlay, you can now stream video from the Photos app, including iTunes previews, enabled third-party apps, and websites, to an HDTV via Apple TV;


• The Safari browser is now powered by the Nitro JavaScript engine, which Apple claims can run JavaScript twice as fast as iOS 4.2;


• You can share your iTunes library, including music, video, podcasts, and audiobooks, on any compatible device in the home, with no syncing required;


• The side switch on the iPad can be customized to lock screen rotation or mute volume;


• Your iPhone 4 can be used as a personal 3G hotspot, providing connectivity up to five other devices: Macs, PCs, iPads, or any other Wi-Fi-capable devices.