The new Android SDK (computer link) is now available for download in Windows, Mac OS X (intel) and Linux (i386) formats. The new SDK replaces version 1.6.
According to the Android site (computer link):
Android 2.0 is a major platform release deployable to Android-powered handsets starting in November 2009. The release includes new features for users and developers, as well as changes in the Android framework API.
For developers, the Android 2.0 platform is available as a downloadable component for the Android SDK. The downloadable platform includes a fully compliant Android library and system image, as well as a set of emulator skins, sample applications, and more. The downloadable platform is fully compliant and includes no external libraries.
The site also includes videos, a reference section, a developer guide, blog, and community section.