Google isn't telling me any secrets about its plans for Chrome OS. Indeed, I'm not even one of the 60,000 or so people that Google has given a Cr-48 Chromebook prototype to play with. Even so, unlike my good friend Mary Jo Foley, I think I know exactly who Google has in mind for its Chrome OS Linux desktop system.

I see Google as targeting two different, very different, audiences with Chrome OS. The first group are office workers. The other is those hundreds of millions, perhaps a billion plus, users who really don't know the first thing about to use a computer safely even as they use them every day.

In this set-up, a company would pay Google a fee, just as some do now for Google Apps for Business. In return, the company gets the 21st century version of a thin-client desktop.

This is an idea that goes all the way back to terminals to mainframe computers. While PCs put this idea into a niche market for decades now, some CIOs and administrators still yearn for it. The reasons for this are quite simple: It puts IT back in charge of the office desktop.

The security is set-up from a central control, the management decides what applications users will run and so on. This idea comes back over and over and... well you get the idea. If you've been in IT for a while, you've seen this notion from Oracle as network computers; and from who knows how many vendors as the diskless workstation or as thin-clients.

In the past, it's never taken off for several reasons. From an IT standpoint, one of the big problems has always been that the server proved to be a single point-of-failure. Google will try to get around this by using its cloud services in place of a server.

Users, of course, given a choice between a PC, where they get to set up the wall-paper just so, add their favorite application and a smart-terminal where they have no control over the system always went for PCs. Chrome OS will give users more control over their environment than some earlier thin-client approaches. Whether that will be enough to make users happy is another matter.

The other audience is Jason Perlow's grandpa. There are hundreds of millions of users just like him and not all of them are old. They have no more clue about to use a computer safely than I know how to land a 747.

If you read ZDNet regularly, you may not realize just how many people there are like that who think that their computer is a magic box. Forget about knowing the difference between Windows and Linux, they can't tell the difference between the Web browser and the operating system. That's where Google Chrome OS comes in.

With Chrome OS the operating system and the browser really are one. If they can use a Web browser, and almost anyone can do that these days, they'll be able to use Chrome OS.

More to the point, as Perlow pointed out, Chrome OS is "totally maintenance free, all the apps and the data are cloud driven, and you can't break the OS even if you try." Well actually you can but it's beyond the ability of most tech illiterates. Chrome OS also uses a sandbox security system that goes a long way towards making sure that no matter what an idiot user clicks on he or she can't install malware or otherwise get into trouble.

Put it all together and you have a Linux-based operating system that's ideal for either office-workers or people who need a computer but don't know the first thing about how to use one safely. Is that you? Probably not. It's certainly not me. But, it does describe hundreds-of-millions of users. For them, Chrome may be all the operating system they'll ever need.