GIMP 2.6 changes are mostly internal
The GIMP -- the GNU Image Manipulation Program -- is one of the flagships of free software. On October 1 the project released version 2.6, with many new and improved features. Most of the user-visible features are just polish; the real changes are lurking under the hood.
How you install the GIMP 2.6 depends on your distribution. Check your package manager to see if it's already available in a repository. If not, you can download it and build it from source using the usual ./configure && make && sudo make install routine.
After starting it the first thing you'll notice is an additional empty image window appearing next to the toolbox. This is part of GIMP's UI restructuring, which we'll take a detailed look at in a moment.
One of the most useful additions to the new version is support for a polygonal selection mode in the free select tool.