The Android 2.2 platform is now available for the Android SDK, along with new tools, documentation, and a new NDK.
Android 2.2 is a minor platform release including user features, developer features, API changes, and bug fixes. For information on developer features and API changes, see the Framework API section.
For developers, the Android 2.2 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 includes no external libraries.
You can refer to my article to know how to Install Android SDK on Eclipse 3.5 Galileo, in Ubuntu 9.10. Or, if you have install Android 1.6 SDK or later version, you can refer to another article to upgrade Android SDK using Android SDK and AVD Manager.