We have two separate power runs to each rack regardless of standard rack mount servers or blades so power redundancy is a non issue.
The chassis are fully redundant and offer better power consumption and lower cooling needs as compare to equivalent rack mount servers
Cable consolidation through, consolidated iLo ports, integrated ethernet and fibre switches can also amount to large savings; reducing the drain on core switch ports.
We worked very hard with the vendor on pricing and our blade environment is cheaper than a standard rack mount environment.
Also have a look at the virtual connect modules. There is some very cool functionality there with the virtualization of MACs and WWNs.
Basically a rack for us is a series of 4 chassis that will fill up as needed. As I said before it is not for small shops if you just don't have the capacity requirements but for most others you will see a move in this direction
Also, have a look at HPs datacentre consolidation project. They are moving from something like 86 datacentre to 6 that will be built on a foundation of Blades + SAN + VMware. That was the ultimate validation for us and our direction once we saw we were doing exactly what they were.
