The current stable Psycopg release is 2.5.4:

There is currently no testing release.

See the install page for instructions about how to install Psycopg from source.

Windows packages

Jason Erickson maintains a packaged Windows port of Psycopg.

If you want to build on Windows yourself, here is an article with some tips.

Mac OS X Packages

Psycopg is available as a fink package in the unstable tree: it should be possible to install it with:

fink install psycopg2-py27

The package is also available on MacPorts: try:

sudo port install py27-psycopg2

If you want to build Psycopg from source, take a look at these articles.

Older versions

All the Psycopg releases (both branches 2.0 and the now obsolete 1.0) are available for download.