PostgreSQL 9.2 can scale linearly to 64 cores, index-only scans, advances in lock management, and reduction in CPU power consumption, this new release is much faster and can scale further than before. Read queries can be up by 4x faster, index-only scans for data ware-housing queries can be 2 to 20x faster, and there can be about a 5x improvement in data writes. PostgreSQL 9.2 also supports cascading replications to run larger stacks of horizontally-scaled servers.
PostgreSQL 9.2 also presents native JSON support, covering indexes, range types, and much more. The new PostgreSQL 9.2 features are covered in greater detail on their Wiki what's new page.
More 9.2 release information is available from PostgreSQL.org, including the release notes for this popular open-source database.