Midori operating system is the code name for a microkernel-based operating system written as managed code, being developed at Microsoft, mooted as a possible successor to Microsoft Windows by many.
Midori will use the Internet to operate and data will be stored on central Microsoft server. It will remove the role of a single PC. From the BBC article:
Microsoft has kicked off a research project to create software that will take over when it retires Windows. Called Midori, the cut-down operating system is radically different to Microsoft's older programs. It is centred on the internet and does away with the dependencies that tie Windows to a single PC. It is seen as Microsoft's answer to rivals' use of "virtualisation" as a way to solve many of the problems of modern-day computing.
I don't know about Windows user, but Linux will be there as a desktop operating system along with other alternatives. I'm not going to store my data on 3rd company corporate network, I don't trust 3rd party for my data, period. Imagine security related problems. That's why, I don't use any of the Web 2.0 stuff including Google docs, flickr and so on.