Actually there are many different software/hardware solution out there for this. 99% of them are designed for use in education.
http://www.userful.com/ -- one example
There is also another, more reputible company. It starts with an N...something. I can't for the life of me remember it right now.
Ecentially, you buy their hardware/software and then you are able to hook it up to one PC and then hook up multiple monitors/keyboards/mice.
I agree that it is really old technology that is making a major comeback in the education world because of the cost savings. 10 upper-end PCs can become a lab of 50+.