Linux World had an interview with Linus Torvalds, here's a snip:
COMPUTERWORLD: What did you want from the public release of Linux? Was it money?
Torvalds: It certainly wasn't money, since the original copyright was very strict about that. It wasn't the GPLv2, it was my own "no money at all, and you have to give sources back" license.
CW: Was it for fame or for fun? Could you imagine the revolution you were about to start?
Torvalds: No, I didn't think that Linux would become as big and popular as it is now, so it wasn't really fame either. I'd like to say it was for fun, and that probably comes closest, but it might be more accurate to explain why I thought it would be fun. The releasing itself wasn't anything particularly fun, but what I was really looking for was feedback and comments..