Google has released the Android Development Kit 1.6. According to Xavier Ducrohet:
Android 1.6, which is based on the donut branch from the Android Open Source Project, introduces a number of new features and technologies. With support for CDMA and additional screen sizes, your apps can be deployed on even more mobile networks and devices. You will have access to new technologies, including framework-level support for additional screen resolutions, like QVGA and WVGA, new telephony APIs to support CDMA, gesture APIs, a text-to-speech engine, and the ability to integrate with Quick Search Box. What's new in Android 1.6 provides a more complete overview of this platform update.
The Android 1.6 SDK requires a new version of Android Development Tools (ADT). The SDK also includes a new tool that enables you to download updates and additional components, such as new add-ons or platforms.
You can expect to see devices running Android 1.6 as early as October. As with previous platform updates, applications written for older versions of Android will continue to run on devices with Android 1.6.