Check out our webthree-umbrella-cross Github repo.
Yesterday I spent some time improving that front-page so that the project is close to self-describing. We’re getting very close to having working binaries, and are attacking multiple platforms in parallel. We have (currently broken) releases which anybody is welcome to use to help to with our debugging efforts.
We’re working with EthEmbedded to get this cross-build infrastructure working for single-board-computers as well as for our mobile/wearable target devices. Join us in the Gitter porting channel if you would like to help out, or just follow along.