Few people really know much about PageRank beyond the general idea. In Google's case, I think they talked about PageRank more because they had written a paper on it and it was already public whether they talked or not.
But if you observe, beyond the original paper, little is known about PageRank from Google. There are plenty of guesses--right and wrong--that can be pieced together to form a narrative of the changes and evolution in PageRank. But nothing official from Google. And probably for a reason.
Ask Jeeves (or maybe Yahoo) tried a big "The Algorithm" marketing campaign and that clearly got them nowhere. I think if we're talking about marketing the "I'm feeling lucky" button was more of a boon to virality than PageRank.
Choosing PageRank was probably a slight lapse in integrity in my post, but undoubtedly there's been a whole bunch of other examples in Google's history which do fit the mold (GFS, MapReduce, Pregel, etc).
1. PageRank
2. ???
3. Profit
(Worth the potential downvotes.)
1. Hey everybody, check out this new search engine with a genius algorithm called "PageRank" that returns much more relevant results!
2. ?
3. ?
In other words, Google is a prime example of what zaidf is saying. PageRank was a huge marketing hit. Over 10 years later, it's still the first thing anyone mentions when they talk about Google's competitive edge, yet this has been a fiction for ages and may largely have been so from the beginning. How much of a technical edge was it really, compared to the other things Google did right? That remains totally obscure (see 2 and 3 above).