Today at Google I/O, Google announced "Brillo," a new lightweight operating system for IoT devices. The OS is based on a stripped-down version of Android, which was previously rumored to work with as little as 32 or 64 MB of RAM.
The OS is supposed to work with minimal resources in things such as "smart" door locks or lightbulbs. Because it's based on Android, it already has broad support from most chip manufacturers. Because it's a stripped-down core of Android, it also means that it's easier to secure.
The OS will support Wi-Fi, Bluetooth Low Energy as well as Google and ARM's "Thread" mesh networking protocol. Device manufacturers will be able to manage and update Brillo devices from a centralized management console. Hopefully, that means Brillo IoT devices won't be left behind with years of accumulated security vulnerabilities.
Brillo also seems like a more or less direct competitor to ARM's own mbed OS for the Internet of Things. Initially, though, Google will likely focus its efforts to expand support for Brillo in homes, while mBed could be used for things like street lights.
Home automation is where the two overlap, and because Google is closer to end users than ARM, it's likely that users will prefer to interact with Brillo in their homes rather than the mbed OS. Another advantage for Google is that Brillo devices will interact with Google-owned Android smartphones.
Google also announced "Weave," which is a cross-platform (doesn't need Brillo for it to work) communications layer that can help IoT, smartphones and clouds communicate with each other. Weave will use a common vocabulary called "schema" that can be understood by different devices. For instance, a smart door lock could use the standardized Weave schema for door locks to show whether it's locked or open, and then its state could be interpreted by a smartphone or a cloud service.
The developer preview for Brillo should be available in Q3 2015, while the full stack for Weave will be available in Q4 this year.