Version 0.9 Ganymede
Please read this entire document for important information about this release.

Whats new in Version 0.9?

Python bindings - This is the major focus of this release it is now possible to create plugins using python. It is also possible to create GIS enabled applications written in python that use the QGIS libraries.
Removed automake build system - QGIS now needs CMake for compilation.
Many new GRASS tools added (with thanks to http://faunalia.it/)
Map Composer updates
Crash fix for 2.5D shapefiles
The QGIS libraries have been refactored and better organised.
Improvements to the GeoReferencer

Special Requirements Qt 4.2.2 is required. The Expat XML Parser is required for the GPS plugin. This vastly improves the speed and memory management when loading GPX files. The raster georeferencer plugin requires the GNU Scientfic Library (GSL). GSL and Expat are optional and required only if you want to use the georeferencer or GPS plugins respectively. SQLite is always required.

Known Issues in this Release

General

Project files from previous versions of QGIS will likely not work.
Some internationalization (translation) files may be incomplete.
QGIS is not bug free - we make no assertions as to its fitness for use for any particular purpose. Use entirely at your own risk.

OS X Specific

Due to a limitation in the Quicktime graphics engine, there is a limit on the number points allowed per feature. See the Readme that comes with the OS X dmg

Windows

Reporting Bugs

If think you have found a bug, please consider reporting it to the development team. The steps to report a bug are:

Go to the Bug Tracker at https://svn.qgis.org/trac
Read Using Trac With QGIS to learn about the submission process
Review the list of current issues to make sure your bug has not already been submitted. If it has, review the submission and see if there is anything you can add to the bug report to aid the developers
If your bug has not been reported, create a new ticket, making sure to either login to trac or provide your email address. Tickets lacking contact information are subject to deletion.

Installation Guide: How to build and install QGIS. The guide is available as part of the User Guide.

User Guide: The definitive guide to using QGIS (be sure to read this!). The User Guide is available in pdf format.