iOS 4.1 has arrived. What makes this Apple OS so great?

On Wednesday, Apple released iOS 4.1, an update to the iOS 4 operating system that shipped in conjunction with the Apple iPhone 4. The new OS, which is available for the iPhone 4, the iPhone 3GS, the iPhone 3G, and some iPod Touch models, should automatically become available for update when you connect your device to iTunes.

(A caveat: Certain functionalities, including application multi-tasking, are only available on certain devices, such as the iPhone 3GS and iPhone 4.)

So what's new with iOS 4.1?

Well, for one, Apple has patched up a whole lot of bugs, including a problem with the proximity sensor that led to accidental call hang-ups, several vulnerabilities in the WebKit framework, and an issue with FaceTime that apparently made it relatively easy for skilled hackers to redirect calls made with the video chat application.

Better yet, iOS 4.1 also allows users to upload HD videos to YouTube over a Wi-Fi connection, and opens up access to Game Center, a multi-player gaming platform. (Slogan: "It's your world. Everyone else is just playing in it.")

Apple launched the iPhone 4 in June. The handset was greeted warmly by reviewers, but skewered in the press for an apparent problem – the "death grip" – with the wraparound antenna. Much noise ensued, and eventually, Apple CEO Steve Jobs announced that Apple would issue free bumper cases to all eligible consumers. The iPhone 4 has sold briskly, Apple says, and remains in high demand around the country.