What you are describing is part of MacOS X, it's called XGrid... LAtency of the internet make it unsuitable for WAN usage, but if you have a gigabit network at home it's a treat.
Apple's Logic Pro 7.2 uses this system to allow all Macs on your Lan to help out processing the audio signal. I currently use 3 Macs on a Gigabit network just for audio processing (Two MacBook Pro's and a PowerMac G5). It works brilliantly and all in realtime!
-Edit- Opps beaten to it :-)
