What is Multiplicity?  It's a program that is designed to multiply the computing power of individuals by allowing them to manage multiple computers as if they were a single computer. 

It works by having N computers and at least N monitors but only 1 keyboard and mouse.  The keyboard and mouse are hooked up to the primary computer and with it, the user then controls each of their computers by sliding the mouse over onto the monitor that is attached to the corresponding computer. So in effect, it's like a multi-monitor PC except that I'm multiplying my overall computing power which in turn improves my productivity.

For power users, Multiplicity is the logical destination to maximize what one can do in a given moment of time.  I say that as someone who, for years, bought SMP machines with the hope of being able to never be interupted in what I was doing by the computer.  OS/2 SMP, NT SMP, etc. never quite did that. I always found myself having to wait for something. This become particularly noticeable when I started tossing more monitors onto a single PC.

Multiplicity eliminates that by letting magnify what I can do by simply tossing more "boxes" under the desk. And let's face it, many people these days have more than one PC.  Sure, at least one of them is probably not state of the art, but it's probably more than enough for reading mail, doing instant messaging, etc.

With Multiplicity, much of its goodness is in its usability (and for those who doubt this, they'll be able to download a demo version because if you're sitting there thinking "What about KVM switches?" or "What about program X?" then the solution is being able to see it for yourself).

It's not just that it provides a universal clipboard between all your machines. It's not just the idea that you can now control a PC and a Mac together.  It's not just that you can copy files and folders between machines with a simple copy and paste action. It's in the details. It's in the UI.

So how would one use Multiplicity? Kris Kwilas, who works at Stardock, has a few examples he can rattle off the top of his head:

Remote desktop, radmin, VNC, and the like are great solutions for bringing the remote desktops to your main PC.

Multiplicity needs another monitor hooked up to secondary PC (up to 6 of them). There's no getting around that for the moment (by design). If you don't have 2 PC's and 2 monitors, it's of no use to you.

Let me give some examples. Until you've used it, imho, you don't even realize that you've been missing something without it. Which is what the trial version will be for!

- Have you upgraded your main PC at home but the other one isn't quite ready to collect dust in the corner of your office? Have you ever emailed yourself a file or burned a CD to get it 6 feet across the desk to another machine?

- Do you have a laptop or a tablet? Are you on the road and when you come back to the office, you want to control everything from one place?

- Would you like to play games on one PC will still being able to surf the web and IM on the other? Or play multiple accounts in a MMO game at once (yes, people do this, I was surprised too!).

- Do you develop software for a living or hobby and need to test it elsewhere? Are you an artist and want to be able to work on something else while a render or filter happen?

- Do you have to test software on multiple configurations? Some people do have a half-dozen mice and keyboards on their desk.

- Do you need more "desktop" to monitor something that can go on a secondary machine while you continue to work uninterrupted in your main one?

As for myself, I use it at work because I do a lot of compiling one one machine and a lot of graphics design on the other and those of you in my shoes know how that can be.  I am thinking of throwing a crap box for a third and having it dedicated to instant messaging and chat and such.

It really came in handy on my recent media tour. I needed to get a bunch of screenshots of GalCiv II. But every time I ALT-ESC'd out of GalCiv, it would crash.  So what I ended up doing is having GalCiv II run on Machine A, hit print screen, then move my mouse to machine B and paste the screenshot into Photopaint.  Then I saved the files, zipped them up and copied them back to Machine A by right clicking on the ZIP file, choosing copy, then moving my mouse over to Machine B where I have my protable hard drive already hooked up, right clicking and choosing paste. And sure, with network shares I could have copied too but compare the productivity difference in just that one trivial example.

I also use it when my son and I play World of Warcraft.  We have two accounts. So he plays and I play. We sit next to each other (killing wolves and bandits together - father and son ).  But he's only 8 so he gets stuck.  He has the keyboard and mouse hooked up to his computer. But when he gets stuck, I can have Multplicity set to switch desktops with a hot key and then zip over there and help him cast a spell or deal with a complicated issue and then zip back to my desktop to keep going.

Most of the time though I use it in totally seamless mode. That is, just like a multi-monitor setup, I just move my mouse to the other screen and control that box. In our lab there are configs with many machines hooked up to it. It's very handy for testing.

That isn't to say we have dumped our KVM switches.  Our server room uses that and it works great for that.  It's not really designed to compete with that. But there are probably people who use KVM switches who would be better served with Multiplicity just as there are people who might be using VirtualPC who might be better served this way too. There's a lot of potential overlap depending on what you're doing.

Try out Multiplicity for yourself.