Honestly, the whole idea of "greatest innovators" seems like the wrong question to be asking. Innovators as they seem to be outlined by the poll (Steve Jobs and Thomas Edison certainly fit this description) seem to be people who hoard patents in order to create a profitable market for a product that they control. In other words, people who use technology to make boatloads of money.
Is this really something that we should be considering praiseworthy? I mean, Steve Jobs was an important figure in the technology industry, and innovation was an important part of what he did (his specific sense of vision wouldn't really have applied to, say, investment banking). But first and foremost, Jobs was a businessman, and his motivations were always directed in that manner -- towards earning the greatest profits. Can anything that he did really be said to even be a fraction as important as the work of, say, Alan Turing, the British mathematician and cryptanalyst whose work laid the foundation for the very field of Computer Science? Turing's not winning any popularity contests and you don't see people carrying around phones with his company brand logo on it, but there's a good reason why the award issued every year to select scientists for their contributions to computing is referred to as the Turing Award. That award, incidentally, was won by Dennis Ritchie (who was mentioned by others in this thread) together with Ken Thompson for their work in deveoping unix.
Similarly, I'm sure there are many great medical researchers working for big pharmaceutical corporations which have portfolios of hundreds of gene patents, but if you compare them with Jonas Salk, who not only developed the polio vaccine but insisted upon giving it away for free, who is the truer scientist? You see, in my mind, once you start thinking about profit, you lose something already of yourself. Sooner or later you're going to have to compromise on scientific principles of objectivity if you're concerned about what will make the most money for you, or your investors, or shareholders. Innovators, ironically, often thrive upon stifling the innovations of others so that they can take the credit for themselves -- something that Edison excelled at.
Maybe if you ask people who the greatest scientific researchers are, you'll get some real answers containing people who actually contained a brilliance going far beyond simple business acumen. At least, you'll get a list without Mark Zuckerberg.