Many regular readers are familiar with the new Galileo board from Intel. This open-hardware board is based on the Quark SoC and provides Arduino compatibility with very high performance and great power management. (More information about the Galileo)
It may not be quite as commonly known that the Galileo is fully supported in the Yocto Project. The software downloads page for the Galileo contains drivers and images as well as links to the Galileo BSP and a full YP-based development environment. (Some community advice on using YP with Galileo)
This smaller board complements CircuitCo's Atom-based MinnowBoard project, which this week announced a new board called the MinnowBoard Max. The Minnows are also very well supported in YP.
All of these boards are open source hardware.