It has been a busy week for Apple Inc. (NASDAQ: AAPL), the world's most valuable tech company. On Wednesday, it unveiled its next generation iPad, which features a higher-resolution display, a new processor, and support for high-speed 4G LTE data networks.

The new iPad comes with an updated software, iOS 5.1.

Users of existing Apple mobile devices -- including the iPhone 4S, older iPhone models, the iPod and iPad -- can now have the same software that's running the new iPad by downloading iOS 5.1 at iTunes.

You can download the update via iTunes of if you have iOS 5.0 installed OTA (Over The Air) by going Settings > General > Software Update.

Features

iOS 5.1 contains improvements and bug fixes, including:

* Japanese language support for Siri (availability may be limited during initial rollout)

* Photos can now be deleted from Photo Stream

* Camera shortcut now always visible on Lock Screen for iPhone 4S, iPhone 4, iPhone 3GS and iPod touch (4th generation)

* Camera face detection now highlights all detected faces

* Redesigned Camera app for iPad

* Genius Mixes and Genius playlists for iTunes Match subscribers

* Audio for TV shows and movies on iPad optimized to sound louder and clearer

* Podcast controls for playback speed and a 30 second rewind for iPad

* Updated AT&T network indicator

* Addresses bugs affecting battery life

* Fixes an issue that occasionally caused audio to drop for outgoing calls

Siri has been updated for the benefit of the Japanese users. . Siri now will be able to understand and talk back in Japanese. The app remains exclusive to the iPHone 4S though.

As to Photo Stream, the app was launched as part of iCloud and iOS 5. But users quickly complained that once a photo was uploaded, they couldn't delete it. iOS 5.1 adds the delete option.

iOS 5 added a lock screen shortcut that allowed users to quickly shoot a photo without having to unlock the iPhone. While the shortcut wasn't always visible, iOS 5.1 now makes the shortcut present at all times.

iOS 5.1 has updated the camera app for the iPhone to highlight all faces that it detects when you're trying to snap an image. As to the iPad, the camera shutter has been transferred from the menu bar at the bottom of the viewfinder to the right side of the frame.

For information on the security content of this update, please visit this ">Web site.

Battery Bug

The battery bug-fix could be the most useful addition to iOS 5.1

The battery life issue has hounded the iPhone 4S and other devices that has been updated to iOS 5. The iOS 5, which was made available for Apple mobile devices in October, boasts of 200 new features that, according to Apple, takes "a mobile operating system that was already years ahead of anything else and moving it even further ahead.

"A small number of customers have reported lower-than-expected battery life on iOS 5 devices," Apple acknowledged in November.

Weeks before, Apple released the iPhone 4S, which sports the same 3.5-inch screen as the iPhone 4s; an 8-megapixel, 1080p high-definition camera; an A5 dual-core chip processor that has a graphics processor is seven times faster than the previous model's; 512 MB of RAM; and iOS 5.

The iPhone 4S is stated to have 200 hours standby time (iPhone 4 300 hours), 8 hours talk time on 3G (iPhone 4-7 hours), 14 hours talk time on 2G, 6 hours 3G browsing, and 9 hours Wi-Fi browsing. But users have been complaining that the device's battery does not last as advertised.

Apple later released iOS 5.01. to diagnose and address the issue. However, the update has failed to completely resolve the issue.

Has iOS 5.1 addressed your battery issues? Tell us.