While Apple announced the software's release early Monday, it finally arrived around 10 a.m. Pacific, 1 p.m. Eastern. The update is available for iPhone, iPad and iPod touch users through iTunes.
"iOS 4.2 makes the iPad a completely new product, just in time for the holiday season, Apple Chief Executive Steve Jobs said. "Once again, the iPad with iOS 4.2 will define the target that other tablets will aspire to, but very few, if any, will ever be able to hit."
iPad users can now run their favorite apps and switch between them instantly, while preserving iPads legendary battery life. Users can organize their apps with drag-and-drop simplicity using Folders, and Mail now features a Unified Inbox, fast inbox switching and a threaded message view.
iOS 4.2 will also bring Game Center to the iPad. Game Center allows iPad, iPhone and iPod touch users to challenge and play friends or be matched automatically with new opponents, showcase their scores and achievements, and discover new games their friends are playing.
Another new addition is AirPlay for streaming music, video and photos wirelessly from iPad, iPhone and iPod touch to Apple TV. iOS users also will be able to use AirPort Express and AirPlay to stream wirelessly to any stereo or powered speakers, or directly to AirPlay-enabled speakers coming to market in the months ahead.
The Apple TV received a software update on Monday to enable AirPlay functionality with mobile iOS devices. The direct update can be applied over Ethernet or Wi-Fi through the set top box.
iOS 4.2 also brings AirPrint, a next-generation Wi-Fi print architecture that aims to simplify printing by completely eliminating printer drivers. A selection of AirPrint enabled printers including the HP Photosmart, HP LaserJet Pro and HP Officejet will be the first to support printing direct from iOS devices. iPad, iPhone and iPod touch users can simply tap to print their documents or photos wirelessly to any printer that supports AirPrint.
The Find My iPhone (or iPad or iPod touch) feature is now free to use without a MobileMe subscription and helps you locate your missing device. The Find My iPhone app is a free download on the App Store and lets users easily locate a missing device on a map and have it display a message or play a sound. Users can even remotely lock or wipe data from a lost device to protect privacy.
Other new features that iOS 4.2 brings to the iPad include: the ability to rent TV episodes directly to iPad using the iTunes App with a 30 day viewing window and a 48 hour session window once playback is started; the ability to easily find and highlight specific words and phrases on web pages in Safari®; enhanced enterprise support so businesses can take advantage of stronger security features, new device management capabilities and improved enterprise integration; industry-leading accessibility enhancements; and support for 25 additional languages, including Korean, Portuguese and Traditional Chinese.
For more, see AppleInsider's extensive coverage of iOS 4.2:
Apple issues iOS 4.2.1 golden master for iPhone, iPad to developers
Apple's release of iOS 4.2 held up by Wi-Fi issues - rumor
Inside AirPrint: How to add iOS printer sharing back to Mac OS X
Test shows Apple's iOS 4.2 further improves iPhone 3G performance
First look: Apple's iOS 4.2 golden master with AirPlay, AirPrint, bugs
First look: Apple's iOS 4.2 for iPad and iPhone
First look: AirPrint wireless printing with Apple's iOS 4.2