The Parallella board will cost $99 and offer 50 GFlops/Watt, consuming a maximum of 5 Watts.
Not quite. The 50 GFlops/Watt figure is for the Epiphany-IV chip, this project says it will use the older Epiphany-III.
It looks like the Parallella will use a 16 core device delivering 32 GFlops, or 6.4 GFlops/Watt - still rather impressive though!
Nigle