NOTE: QGIS packages are now available from qgis.org!
Mac OS X installers for QGIS. Install the Current version to stay up to date on features. Install the Long Term Support version for feature stability for a year.
Install Note: OS X security may block installation, as I’m not an “identified developer” (ie not paying Apple to develop software). There a simple way to force it to install – right-click the installer file and select Open, this will trigger an extra option in the security warning to install it anyways. You only have to do this once, the system will remember the QGIS installer for any future installs (new major versions may reset this).
WARNING: QGIS will crash if Qt4 developer components are installed in the standard /Developer location. Either rename /Developer/Applications/Qt/Plugins or uninstall Qt before running QGIS.
Other Python Modules are available for plugins