Typically, a better approach is branch and bound search using a variant of R-tree or Octtree, especially with axis aligned bounding boxes or circles. Ray casting does not scale to many points while more advanced space partitioning does.
GeoHashing is a kind of binning technique.
Then there are manual volume hierarchies and partitioning based on similarity. Each solves a different problem.
404 and nothing in google cache / archive.org.
Oh no, It looks like my deploy failed midways through after. I probably should have left it as-is after posting to HN. :)