> The code to gevent-ise psycopg2 connections is about 10 or 15 lines, iirc.

Because psycopg2 has supported async OOTB since 2.2 by exposing a pollable socket: http://initd.org/psycopg/docs/advanced.html#asynchronous-sup...

There are limitations though, as noted by the docs: COPY and LOs don't work.