As I mentioned in a previous blog post, trying to find pages in the PostgreSQL documentation using Google doesn't work very well: most often, one gets links to older versions.
A recent thread on pgsql-performance (somewhat off-topic for that mailing list, but that's where it was) suggested that perhaps we could use Google's canonical URL feature to work around this problem.
Another suggestion was that we ask people who link to our docs to link to http://postgresql.org/docs/current/ (or some sub-page) rather than linking to a specific version (e.g. the same URL with 8.4 in place of current). That way, as new versions come out, everyone's links will still be pointing at the latest version of the docs, helping the new versions accumulate "Google karma" more quickly than they would otherwise. Or at least, that's the idea: I have no idea whether it would actually work.