Android Developers Blog: Android 1.6 SDK is here
Android 1.6 SDK is available for download. 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.
Source: Android Developers Blog: Android 1.6 SDK is here
Android 1.6 Official Video