If Google went around telling everyone about their Pagerank idea, writing about it online, etc, do you think this would be inconsequential to their success?
Of course, PageRank was only one of many relevant innovations. A key one was the open bidding for ads. Another was focusing on a high-quality user experience, which included no banner ads and highly relevant search results ads. Both of which were totally visible to competitors, and only came well after the business was underway.
They have kept two major sorts of innovation secret. One is their aggressive pursuit of very low cost computing infrastructure. The other is the relentless improvements to search quality. PageRank is only a small part of that now. That IP has a ton of value. Not because of some secret Big Idea, but because they have taken a lot of little ideas and relentlessly winnowed them, yielding actual knowledge.
