Google today launched Google Wear, its customised version of Android for wearable devices. While we won't see any Wear-powered watches until later in the year, there's already a developer preview to start building apps for the platform.
Wear apps rely heavily on voice input, using the "OK Google" command that's already familiar to owners of recent Android phones. Google has added support for Wear to the Android emulator, enabled access to new Wear-specific APIs, and is promising a full software development kit (SDK) later this year. You can sign up for the preview, or hit the Google announcement post for more details.
Android Wear Developer Preview Now Available [Google Developers Blog]