GIMP 2.6 open source image editor launched
One of the most noticable changes is that the main menu items have been moved from the toolbox window to the image window so that you can access most options in one place. Another major change is the ability to pan beyond the border of an image. The free select tool has been tweaked so that it now supports polygonal selections, and there are new brush dynamic options that let you tweak the size, opacity, pressure, and velocity of brush strokes. GIMP 2.6 also uses GEGL for processing most color operations.
You can find a complete list of changes in the release notes.
GIMP 2.6 is available for download via FTP. It's not yet available in the Ubuntu repositories, and there's no Windows installer yet, so you might want to wait a while before installing GIMP 2.6 unless you're comfortable compiling applications from source.
Update: The Windows version is now available for download.