Android 2.3 SDK :

http://developer.android.com/sdk/android-2.3.html

New User Features:
1.) UI refinements for simplicity and speed
2.) Faster, more intuitive text input
3.) One-touch word selection and copy/paste
4.) Improved power management
5.) Control over applications
6.) New ways of communicating, organizing

New Developer Features
1.) Enhancements for gaming
2.) New forms of communication
3.) Rich multimedia

New Platform Technologies
1.) Media Framework
2.) New Linux Kernel
3.) New Dalvik runtime