In my opinion blade servers arn't the best solution.
Here's my reasoning for this. I work in a datacentre that has over 800 47u racks (nearly all full). Each rack gets a standard 10amp supply to it. If you put 5 8 port apc masterswitches into a rack, 1 48 port switch and the best part of 35-40 pentium 4 class servers watch that 10amp meter go right upto the top..
Power is becoming a serious issue in datacentre's now and if i we're to load a 47u rack with blade servers i doubt i would fill half of it. While its great having these high density servers there are cons. Most datacentre's supply 16amp max to a rack, this would be pretty much maxed out in my opinion. Plus their expensive and if the manufacturer decided's to discontinue blades on the chassis you have bought then youre pretty screwed.
Great idea, badly executed or just very difficult to execute.
Rob