Google just announced the Google TV add-on for the Android SDK, which allows Android developers to test their applications for display on TVs. Google will release Android compatibility for Google TV with the upcoming update for Honeycomb.
For now, developers can only emulate Google TV (only on Linux with KVM) and not all features are supported yet, Google explained in a blog post. However there are new APIs for TV interaction, such as access to the TV channel lineup. So far, it is more a playground than a full development kit, but developers can start getting comfortable with Google TV. Google provides initial help with UI guidelines for Google TV apps.
While Android Market could be a killer feature for Google TV, users should not expect hundreds of thousands of apps to be available right away. According to Google, apps that require support for device features that are not available on a TV won't be available on Android Market that is shown on TVs. That would include apps that rely on touchscreen data input. In fact, Google said that the initial number of apps for Google TVs will be "small".