It has been interesting to watch the trajectory of the discussion on this. Google introduced Instant in mid-week as a way of anticipating what you're searching for and (like Apple's anticipatory spelling program for its iPhone and iPad) getting you to that search term more quickly --- or, arraying some nearby options to choose out of a drop-down list. It's a sort of result-before-you-type-it mentality.
But some saw it as Google predicting the outcome based on your previous activities and, in Steve Rubel's words, no two people ever getting the same result. The feedback from Google Instant would make you tweak your search in midstream, he (who deserves great respect for his investment in this field) and others argued.
Obviously, SEO isn't dead. Nor is the Web, as Wired provocatively stated last month. Nor are newspapers, as more than a few have been stating for years. But the challenge is to understand how something like Google Instant changes the game and contributes evolution. In playing with it a bit this week --- I'm not a big personal searcher, but I'm a big professional searcher --- I found its intuitive function good, but not as efficient as my own typing for the term I originally wanted. The real-time feedback isn't swift enough, I found, to move me off my first plan.
It's going to take more time to understand the consequences, though. Those early impressions may shift as Google weedles into my searches more often and understands my patterns. For many it will be a welcome addition to the massive reference volume of the Internet. Whether it makes irrelevant the effort to optimize content to get search results that drive traffic is an open question.