Apple has released its latest version iOS, the long-awaited iOS 4.3 update. Available now through iTunes, the update introduces a few vitally interesting new feautres to the iPhone, iPad and iPod touch.

Amongst the biggest inclusions are Home Sharing (the ability to stream audio and video from iTunes on a local network to the iOS device); AirPlay (the ability to stream audio and video from the iOS device to an Apple TV or computer) for third-party developers; and the ability to create a personal WiFi hotspot from an iPhone or iPad with 3G support. 

Headlining the iOS 4.3 update is support for AirPlay across all apps. This feature first appeared in iOS 4.2, allowing Apple's iOS apps to stream audio, video, and photo slideshows to a second-generation Apple TV. Apple opened up the feature in iOS 4.3, which means developers of media apps like Pandora are free to update their wares, if they choose, and offer AirPlay features to users.

iOS 4.3 also brings support for creating a personal hotspot, another increasingly popular feature among other smartphones, and also provided by independent devices such as 3's MiFi. The personal hotspot feature allows your iPhone 4 to act as a portable Wi-Fi router for up to five devices, powered by the device's wireless data connection (you can connect up to three devices via Wi-Fi, three via Bluetooth, and one with a USB cable).

Users locked into a data contract may need a qualifying data plan from your carrier and any necessary hotspot or tethering options to enable this feature. Users with an unlocked iPhone can use the feature without restriction. However, we advise users of this feature to keep a close eye on data charges as most mobile phone companies in the UK are now restricting data usage (with the exception of the Three network and its One plan, which allows for unlimited data).

iTunes Home Sharing, a surprise iOS 4.3 addition that Steve Jobs announced at Apple's iPad 2 event last week, allows iPhone, iPod touch, and iPad users to stream any of their iTunes media from a Mac or PC on the same Wi-Fi network. It's not an over-the-air media sync solution, however, like the Home Sharing feature Apple added to iTunes 9 to make it easier to keep iTunes libraries on multiple computers in sync. If your iOS 4.3 device leaves your home Wi-Fi network, you won't be able to stream iTunes media from your Mac or PC.

Apple claims to have made Safari's JavaScript performance up to twice as fast in iOS 4.3. Sites with interactive features, or rich Web apps like Gmail, should feel noticeably snappier. The company also seems to have relented to user unrest after changing the behavior of the iPad's side switch. Since the iPad shipped almost a year ago, its side switch acted as a display rotation lock. When Apple released iOS 4.2 last November, it changed the switch from a rotation lock to a mute switch, without even offering an option to change it back. Under iOS 4.3, the switch will still default to muting audio, but Apple added a new preference to the Settings app to let users enable the rotation lock behavior instead.

A couple of minor features snuck into iOS 4.3. You can enable Push Notifications for Ping activity, and the iPod app's Now Playing screen offers the options to post about songs and like them on your Ping profile. Also new is a preference to specify how many times an SMS alert is repeated, as well as a conference dialing option to add a pause for entering a passcode.

Missing from iOS 4.3, however, are the new multitouch gestures that Apple asked developers to test on the iPad during the beta period. Gestures like four- and five-finger swipes could switch between apps and reveal the multitasking bar, and a pinch could exit an app and return you to the Home Screen. With the second iOS 4.3 beta, however, Apple clarified that these features were only for testing and would not ship to consumers in the final version. Obviously, they could return in a future iOS update or upgrade, but Apple hasn't stated any plans.

iOS 4.3 is available now as a free update in iTunes for the iPad, iPhone 3GS, the GSM iPhone 4, and third- and fourth-generation iPod touch. As for the Verizon iPhone 4, it runs a custom version of iOS 4.2.6 that includes some features like hotspot support. Comments from an Apple representative to Ars Technica at the iPad 2 event suggest that it might take a little while for Verizon's iPhone 4 to converge with the same iOS version as Apple's other mobile devices.