There have been 'lite' versions of Second Life available for some tablets and smartphones for sometime now, but they only gave you chat access and now Linden Labs has announced that SL Go has been launched.
According to the app download page, SL Go by OnLive (Beta version) is the first Second Life mobile app viewer that
delivers an immersive desktop experience to your Android device over a 4G or
WiFi connection. Optimized for tablets, SL Go by OnLive (Beta version) features
high definition graphics, chat capability and intuitive touch controls for full
movement and camera control over your avatar. SL Go by OnLive (Beta version)
ensures you can stay in touch with your friends from anywhere.