Geographic Information Systems Extensions to PostgreSQL
PostGIS adds support for geographic objects to the PostgreSQL object-relational database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS), much like ESRI's SDE or Oracle's Spatial extension. PostGIS follows the OpenGIS "Simple Features Specification for SQL" and will be submitted for conformance testing at version 1.0.
This is a package for v2.0. In order to upgrade please refer to PostGIS documentation since v2.0 is not compatible with v1.x