Ice Cream Sandwich!
Android 4.0 is here, delivering a unified UI for phones and tablets and innovative features for users and developers. Check out the Platform Highlights for an overview of the new features in Android 4.0.
For more information about API changes, read the platform notes and diff report. If you're new to Android, get started with the SDK starter package.
Android 3.1 includes new developer features such as APIs for USB accessories, MTP/PTP, and RTP, as well as new input events from mice, trackballs, joysticks, and more.
For more information about all the new APIs in Android 3.1, read the version notes.