Is it possible to use one computer for two people at the same time?

10.7: Multi-user Screen Sharing

Other than the above, you can't have two people using two different mice/keyboards/displays plugged into and running the same computer.

 

About 20 years ago there were "X Terminals" that allowed multiple users with graphical displays on a single Unix system. And before that there were text terminals and Teletypes that did the same thing without the graphics. What did them all in as something practical was the the cost of computers basically became the same or less than the cost of these terminals.

So while you can have several people using a Mac (with Lion or Mountain Lion) they would have to be using it from other computers, so there is no cost savings. As you pointed out Linux (and Unix) can do this as well, and so can Microsoft Windows Server (at least some editions).

 

WOuldn't that be perfectly possible with a VM? you can have different mice, keyboards, usb ports for the actual user and a set for the Virtual machine.

 

You don't need a VM, although you could use one.

 

Why would you want that?

There are so many old computers on the market. You can find many computers that will do just about anything with very little tune up needed. Most just need a fresh OS and some cleaning. Many will even be free. If a poor community, school, or whatnot needs computers that's not an issue. There was an article on this about a guy who built a computer lab with free donated computers for his low budget school. Here's the site: https://sites.google.com/site/robertlitteportfolio/

Now if you're looking for processing power, then you don't want to have a couple people sharing the same resources anyway.

 

Yes, it worked 20+ years ago because the terminals were much less expensive than a computer. That's no longer true.