The full SDK for Android 3.0 is now available to developers. The APIs are final, and you can now develop apps targeting this new platform and publish them to Android Market. The new API level is 11.
For an overview of the new user and developer features, see the Android 3.0 Platform Highlights.
Together with the new platform, the SDK Tools (r10) and ADT Plugin for Eclipse (10.0.0) have been updated also.