Transgres is a Mac OSX Mountain Lion application which embeds PostgreSQL and a Java environment. It lives in the menu bar and runs a Postgres server with an extension (pg_jinx) which enables writing Java stored procedures and foreign data wrappers.
The latest binary version of Transgres is available here.
Previous versions are also available at the same location by appending the version number (e.g. Transgres-2.3.4.dmg ).