It's not really a static ranking, though, is it? The PageRank is constantly recalculated when incoming links change.
I don't know what other search engines have implemented because none of them will let me see their code :-) I do believe if they could implement a link-based ranking system without fear of being sued by Stanford they would. I don't know how different a link-based ranking system would have to be from PageRank to avoid getting sued by Stanford, or whether Stanford litigates this when they suspect unlicensed use. I'm guessing they do sue to defend the patent, because Google's royalties for using the algorithm number in the hundreds of millions, a significant amount towards Stanford's endowment.
I don't know what other search engines have implemented because none of them will let me see their code :-) I do believe if they could implement a link-based ranking system without fear of being sued by Stanford they would. I don't know how different a link-based ranking system would have to be from PageRank to avoid getting sued by Stanford, or whether Stanford litigates this when they suspect unlicensed use. I'm guessing they do sue to defend the patent, because Google's royalties for using the algorithm number in the hundreds of millions, a significant amount towards Stanford's endowment.