Доступен третий альфа выпуск PostgreSQL для версии 9.1. Этот альфа выпуск содержит несколько новых главных возможностей, добавленных начиная с выпуска alpha2.
Новые возможности, включенные в релиз alpha3:

• KNN GiST, which implements order-by-operator support for GiST and optimizes nearest-neighbor geographic searches. This will power the next release of PostGIS.
• Additional instrumentation and monitoring facilities, including checkpoint introspection and last-WAL-timestamp information for replication.
• Several new built-in functions: format(), pg_describe_object(), as well as pg_read_binary_file(), which will support the Extensions feature.
• New libpq functions: PQping(), PQlibVersion()
• The capability to produce crash dumps on Windows
• New auth_delay module to introduce a delay on failed authentications and make dictionary attacks more difficult.
• Security hooks on object creation, to support SEPostgres.

Более подробную информацию можно получить в примечаниях к выпуску: http://developer.postgresql.org/pgdocs/postgres/release-9-1-alpha.html