But for how long?
A: OMG! The Electric Bill! THE ELECTRIC BILL!!!
Hmmm... An overclocked 1.66 GHz PowerPC Mac mini (the PowerMac10,2 model) with a 500 gig SATA hard drive in place of the DVD drive never uses more than 32 watts even with the CPU at 100%. At that amount of power usage, you'd be able to use all 50 Mac minis on a single 15 amp, 120 volt circuit, assuming you don't try to turn them all on simultaneously.
I run two PowerPC Mac minis as servers. One of the reasons I chose them, aside from size, is because of how little power they consume. I also just finished working on a film shoot where the main Final Cut project was prepared and footage from an ARRI Alexa was reviewed using a PowerPC Mac mini. They're very handy little machines.