50 watts is definitely an achievement, even if it is just two dual-cores smacked together on the same chip. Server manufacturers are going to be eating these chips up very quickly.

"The new Intel Xeon L5320 and L5310 operate at 1.86 GHz and 1.60 GHz respectively. Energy-efficient Xeon models consume 50-watts of power, which translates to 12.5-watts of power per core. Intel’s regular quad-core Xeon 5300-series consume 120-watts of power."