He poured scorn on the modern trend to treat a new version or update of an operating system as a cause for major celebration and marketing. "An operating system should be completely invisible," he said. "To Microsoft and Apple (it is) a way to control the whole environment ... to force people to upgrade their applications and hardware."

As for his own operating system, Linus said the most exciting developments were Linux's improving green credentials, and a push into mobile devices such as the One Laptop per Child project and Asus's new ultra-cheap Eee PC. The latter, he said, could be a sign that Asian hardware manufacturers were starting to bypass Western commercial operating systems in order to get more control over their products. "That's the primary area that open source (software like Linux) is useful. Software is really expensive to produce and takes years. If you're a hardware company you can't really afford that, you either have to be controlled from the outside or take a pre-existing software stack that you can make changes to."

Linux would be an obvious choice for anything from full-blown PCs to phones or video players, Torvalds said. "I think it's one pretty exciting possibility and it's where the market really wants to go," he said. "The hardware in a mobile device now outweighs anything in a desktop 15 years ago - which is where Linux came from. The (Linux) kernel is already being used in things like cell phones, but the problems have been in the UI (user interface)."

He said he finally saw Linux as able to boast genuine green credentials, after years of hard work. He and fellow programmers modified almost every part of the operating system's core to improve power management. They also enhanced the ability to track down the most power-hungry parts of a hardware and software system. "Everybody wants to be power-aware," he said. "It's not just that you want to be green - it's eating up your batteries."

Linus also praised Google for its contribution to the development of open source software, after a shaky start in which it had been a "black hole" for talented programmers.