1) I think the actual story has elements of both variants--keeping an idea secret until execution, as well as executing on it and improving the idea.
If PageRank was closely guarded in any way, it could have been so that Page and Brin could submit their research paper about it to SIGIR--at which point it would be public. On the other hand, Page and Brin hosted the search engine for anybody to use.
2) As an aside, assuming the page below is the actual paper, does it mean Larry and Brin already have funding at the time they were writing it up? It mentions that users should try the search engine out at google.stanford.edu, but supposedly, it was their first investor who named Google.
If PageRank was closely guarded in any way, it could have been so that Page and Brin could submit their research paper about it to SIGIR--at which point it would be public. On the other hand, Page and Brin hosted the search engine for anybody to use.
2) As an aside, assuming the page below is the actual paper, does it mean Larry and Brin already have funding at the time they were writing it up? It mentions that users should try the search engine out at google.stanford.edu, but supposedly, it was their first investor who named Google.
http://infolab.stanford.edu/~backrub/google.html