The Economist has a good article supporting the argument that big innovation is getting more and more difficult - instead the small improvements can change the world...

"Big companies have a big problem with innovation. This was most vividly described by Clayton Christensen, a Harvard Business School professor, in his book, "The Innovator's Dilemma" (Harvard Business School Press, 1997). Few conversations about innovation take place without reference to this influential work."

"The Oxford English dictionary defines innovation as "making changes to something established". Invention, by contrast, is the act of "coming upon or finding: discovery". Whereas inventors stumble across or make new things, "innovators try to change the status quo," says Bhaskar Chakravorti of the Monitor Group, another consulting firm, "which is why markets resist them." Innovations frequently disrupt the way that companies do things (and may have been doing them for years)."

I'm reading Seth Godins book "Free Prize Inside" that also rides on this argument. So far a very nice book.