Came across an old announcement for a product called "Mammoth S/JDBC"
that claimed to have "support for compressed connection streams"
[http://archives.postgresql.org/pgsql-announce/2003-04/msg00010.php].
Looking for the product page, I found that "S/JDBC was discontinued as
the Open Source version reached the same capability level "
[http://www.commandprompt.com/products/tips].
That's good news -- but I couldn't find any mention of such a feature
in the documentation [http://jdbc.postgresql.org/documentation/head/]?