PostGIS Pre-built Binary Distributions for various OS

CentOS, Scientific Linux, Redhat El, Fedora

​PostgreSQL Yum Repo managed by Devrim Gunduz is the best source for both PostgreSQL and PostGIS binaries

PostGIS 2.0

• ​PostgreSQL 9.1

CentOS 6 PostgreSQL 9.1 Instructions

PostGIS 1.5

• ​PostgreSQL 9.0

​Yum PostGIS 1.5 on PostgreSQL 9.0 Instructions

Windows

You'll see PostGIS various versions available on EnterpriseDb Application StackBuilder after you install

​PostgreSQL 8.4-9.1 Installers

PostGIS 2.1

​Experimental Builds

These are built for PostgreSQL 8.3-9.2 manually for both 32/64bit whenever any major changes

PostGIS 2.1 buildbot builds

• ​PostgreSQL 9.2 (32-bit and 64-bit)
• ​PostgreSQL 9.1 (64-bit)
• ​PostgreSQL 9.0 (64-bit)

PostGIS 2.0

Installers and binaries are uploaded to PostGIS website before they are deployed on stackbuilder ​PostGIS 2.0 Windows install instructions

​PostgreSQL 8.4-9.1 (32-bit and 64-bit)

PostGIS 1.5

​PostGIS 1.5 Windows install instructions

Installers and binaries are uploaded to PostGIS website before they are deployed on stackbuilder

​PostgreSQL 8.3-9.1 32-bit

Mac OSX

PostGIS 2.0

​KyngChaos PostgreSQL 9.1 Lion and Snow Leopard, 64bit only

PostGIS 1.5

OpenGeo Suite

Don't use this if all you want is PostGIS and PostgreSQL. Self-contained comes with PostgreSQL 8.4, PostGIS, GeoServer

• ​OpenGeo Suite Community Edition for 10.5 Leopard, 10.6 Snow Leopard
• ​OpenGeo Suite Enterprise Edition for 10.5 Leopard, 10.6 Snow Leopard: like community but with tech support plan and upgrade support.