The release notes seem to be in two places, with slightly different information.
The page Google sends back for most 8.3 queries http://www.postgresql.org/docs/8.3/static/release-8-3.html and the one you get from the PostgreSQL beta program link http://developer.postgresql.org/pgdocs/postgres/release-8-3.html Not really a big deal as there is the "current as of" heading up top, but until just now I didn't even know there were two places to look. However, neither one of them show what redirect_stderr was renamed to. It says something like "... was renamed to foo. redirect_stderr was renamed to bar was renamed to ..."
