In an official statement posted on its website, the company says: "iOS 4.2 is available today for download for iPad, iPhone and iPod Touch users. It brings more than 100 new features to the iPad including multitasking, folders, unified inbox for email, Game Centre, AirPlay and AirPrint."
The upgrade will unify the software on all three Apple devices and bring software fixes alongside new features.
Arguably the most eagerly awaited addition is the AirPlay streaming service. This will allow you to stream any audio, picture or video content on your iPad or iPhone directly to any AirPlay device.
Apple's AirPlay software will be found on Apple devices such as the iPhone, iPad and new Apple TV but also on AV equipment from the likes of B&W, Denon, JBL and Marantz.
Our first look at an AirPlay-compatible device was the Marantz NA7004 in this year's Awards issue, though the necessary firmware update wasn't yet available.
The Marantz SR7005 AV receiver, tested in our December issue, is also AirPlay compatible.
Given the time difference between the US and UK, we expect the iOS 4.2 upgrade to be available here on iTunes sometime this evening. More details on the Apple website.