Blades never lived up to their initial promise - primarily because each vendor (IBM, HP, Dell) custom designed the blades and rack AND premium priced them

Blades were intended to improve deployment density and drop the price of the servers.

The first step in cutting costs (and comoditizing anything) is to develop standards. Hopefully Facebook's Open Rack (HP has taken a lead Project Coyote) will catch. I'm really hoping the Ciscos of this world, the new ARM guys (like Calxeda) and GPU guys (NVidia) leverage this.
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