UI refinements - The Launcher animation is optimized for faster, smoother transition to and from the Apps list. Adjustments in color, positioning, and text make UI elements easier to see, understand, and use. Navigation to and from the five home screens is now easier — touching the Home button in the system bar now takes you to the home screen most recently used. Settings offers an improved view of internal storage, showing the storage used by a larger set of file types.
Connectivity for USB accessories - Android 3.1 adds broad platform support for a variety of USB-connected peripherals and accessories. Users can attach many types of input devices (keyboards, mice, game controllers) and digital cameras. Applications can build on the platform’s USB support to extend connectivity to almost any type of USB device.
Expanded Recent Apps list - For improved multitasking and instant visual access to a much larger number of apps, the Recent Apps list is now expandable. Users can now scroll the list of recent apps vertically to see thumbnail images all of the tasks in progress and recently used apps, then touch a thumbnail to jump back into that task.
Resizeable Home screen widgets - For more flexible Home screen customization, users can now resize their Home screen widgets using drag bars provided by the system. Users can expand widgets both horizontally and/or vertically to include more content, where supported by each widget.
Support for external keyboards and pointing devices - Users can now attach almost any type of external keyboard or mouse to their Android-powered devices, to create a familiar environment and work more efficiently. One or more input devices can be attached to the system simultaneously over USB and/or Bluetooth HID, in any combination. For pointing devices, the platform supports most types of mouse with a single button and optionally a scroll wheel, as well as similar devices such as trackballs. When these are connected, users can interact with the UI using point, select, drag, scroll, hover, and other standard actions.
Support for joysticks and gamepads - To make the platform even better for gaming, Android 3.1 adds support for most PC joysticks and gamepads that are connected over USB or Bluetooth HID.
Robust Wi-Fi networking - A new high-performance Wi-Fi lock lets applications maintain high-performance Wi-Fi connections even when the device screen is off. Users can take advantage of this to play continuous streamed music, video, and voice services for long periods, even when the device is otherwise idle and the screen is off.
Enterprise support - Users can now configure an HTTP proxy for each connected Wi-Fi access point. This lets administrators work with users to set a proxy hostname, port, and any bypass subdomains. This proxy configuration is automatically used by the Browser when the Wi-Fi access point is connected, and may optionally be used by other apps. The proxy and IP configuration is now backed up and restored across system updates and resets. To meet the needs of tablet users, the platform now allows a "encrypted storage card" device policy to be accepted on devices with emulated storage cards and encrypted primary storage.
Apps
Gallery
The Gallery app now supports Picture Transfer Protocol (PTP), so that users can connect their cameras over USB and import their pictures to Gallery with a single touch. The app also copies the pictures to local storage and provides an indicator to let users see how much space is available.
Calendar
Calendar grids are larger, for better readability and more accurate touch-targeting. Additionally, users can create a larger viewing area for grids by hiding the calendar list controls. Controls in the date picker are redesigned, making them easier to see and use.
Contacts
The Contacts app now lets you locate contacts more easily using full text search. Search returns matching results from all fields that are stored for a contact.
Email
When replying or forwarding an HTML message, The Email app now sends both plain text and HTML bodies as a multi-part mime message. This ensures that the message will be formatted properly for all recipients. Folder prefixes for IMAP accounts are now easier to define and manage. To conserve battery power and minimize cell data usage, the application now prefetches email from the server only when the device is connected to a Wi-Fi access point.
An updated Home screen widget give users quick access to more email. Users can touch Email icon at the top of the widget to cycle through labels such as Inbox, Unread, and Starred. The widget itself is now resizable, both horizontally and vertically.
This is a summary of the full list that can be
found here.
