Android 4.2’s here with a spate of welcome improvements for users and developers alike. Here’s my list of the most important.

Multiple-User Support for Tablets

Samsung Galaxy SNow users can customize their home screen, widgets and apps. Seamless switching enables a quick change for multiple users of the same device. This feature is made possible by the creation of a dedicated user space on the SD card where Google Play helps determine which APKs need to be downloaded. If an app is already on the device, Google Play detects the existing APK instead of downloading it again. This could be a major sales driver of new Android-based tablets. Amazon is already taking advantage of multiuser support on its Kindle Fire HD, which uses Android 4.0.3.

Wireless Display of Content on HDMI-Enabled TVs

Miracast enables seamless, wireless display of content on HDMI-enabled TVs. The device automatically monitors and manages the network connection when displaying an app or other content through a wireless connection. Easy streaming from device to TV will likely be a major selling point for device manufacturers shipping Android 4.2 hardware.

External Device Detection

In addition to easy content display, Android 4.2 boasts automatic external device detection of any attached external display. This would be suitable for business presentations and family photo displays alike. Connection cables and projector troubleshooting could be a thing of the past.

In-Tray Actions for Notifications

Users can take action on notifications right from the tray. No more switching from notifications to apps. While the time savings here are modest, users will likely appreciate fewer clicks required to perform actions based on notifications.

Better Battery Management

CPU cycles are proactively managed in the background. Higher cycles are initiated upon touchscreen action for a boost in power, then slowed to conserve battery life when nothing is happening. Since battery technologies don't change much year to year, this particular feature will be a welcome addition. If you use your phone like I do, your battery needs a charge before the workday is over and again at night before bed.

Premium SMS Service Lockdown

Control over premium SMS services is given to users as apps request permission to use them. Users can accept or block messages on a case-by-case basis.

Improved Permissions Alerts

App update permissions lists will now group similar permissions together for easier viewing. Before accepting a permission, users can click on each request to reveal further information. Also, the new layout is said to be better organized for quick scans.

Security Enhancements at the OS Level

An application verification function checks apps and alerts users to potentially unsafe programs. No modifications of apps are necessary for this to work. Data protection can be as easy as ordering from Google Play.

Always-On VPN

VPN can be configured so that apps don’t have access to a device's network and are prevented from sending data over other networks.

New Dedicated IDE from Intellij

Built upon the community edition of Intellij, this is the second new developer IDE released in two years. Though still considered a rough piece of software, it’s already gained plenty of positive reviews.

Improved Google Play Developer Dashboard

The latest edition of the dashboard contains options for beta testing, translation and analytics. Inside you can define a beta version of your app and hire translation services to convert all content to almost any language.

Nested Fragments

The very latest in Android component reuse comes in the form of Nested Fragments. Dynamic reuse of UI elements can save time.

HDR Hardware Interface

On devices with HDR camera support, the camera scene mode offers a new way to take photos from a mobile device. On devices that support it, the shutter sound can be turned off at will.

Flexible Widgets

Here, there, anywhere with auto-resizing. Widgets now auto-fit on the home screen rather than remaining a static size. Mixing and matching pre-determined widgets is no longer required. Need more? The android developer sessions are available now on YouTube or collected neatly on the Android developer blog.