Google has published Coreboot
support for the Stout Chromebook.
Stout is their codenane for the Lenovo X131e notebook shipped as a Chromebook. The Lenovo X131e Chromebook features a 1366x768 display, Intel Celeron CPU, and 7.5 hour battery life. For a $450+ notebook, it isn't too impressive but at least it's another Coreboot-enabled product.
The Stout support came with this commit
More interesting than Stout is the Chromebook Pixel support