Today on the Google TV Blog the Google TV team released a preview of the Google TV add-on for the Android SDK. While its not a full release, its a step in the right direction. Although this does feel like something that should of been released a long... long... time ago.
The post doesn't give much of a hint about when the OS update will happen but they do say "With the upcoming OS update to Honeycomb, Google TV devices will be Android compatible." So I guess this is their way of saying that all the devices are coming together around one market.