Intel releases low power 4 core Xeon

Intel announces two newcomers in the Penryn Xeon 4 core series.
The L5400 and L5410 run at 2.33 and 2.5 GHz with a 1333 MHz bus have the luxury of only dissipating 50 W.
The bus is a little slower than the Xeon used in the Mac Pro, however the lower thermal load will allow the fabrication of 4 core and even 8 core with a much more compact size. Why not use them in entry towers of a type that some of us have been dreaming about over the years?