We just added gimp 2.6.0 to the testing branch. Here some features to point out:

now everybody knows what I cooked today
Introduction
GIMP 2.6 is an important release from a development point of view. It features changes to the user interface addressing some often received complaints, and a tentative integration of GEGL, the graph based image processing library that will eventually bring high bit-depth and non-destructive editing to GIMP.
User Interface
Toolbox Menubar Removed
The toolbox menubar has been removed and merged with the image window menubar. To be able to do this a window called the empty image window has been introduced. It hosts the menubar and keeps the application instance alive when no images are opened. It also acts as a drag and drop target. When opening the first image the empty image window is transformed into a normal image window, and when closing the last image, that window becomes the empty image window.
Toolbox and Docks are Utility windows
With the empty image window acting as a natural main window, the default window hints for the Toolbox and Docks have been changed to Utility window. This enables window managers to do a much better job of managing the GIMP windows, including omitting the Toolbox and Docks from the taskbar and ensuring that the Toolbox and Docks always are above image windows.
Ability to Pan Beyond Image Border
It is now possible to pan beyond the image border, making image window navigation much less constrained. It is no longer a problem to use the edge of a brush on the edge of an image while being zoomed in, and one can adapt the canvas to any utility windows covering parts of the image window.
Minor Changes
- Renamed Dialogs menu to Windows.
- Keep a list of recently closed Docks and allow reopening them.
- Make opening images in already running GIMP instances work better on Windows.
- You can now enter the image zoom ratio directly in the status bar.
- Added support for using online help instead of a locally installed GIMP Help package.
- Make it possible to lock tabs in docks to prevent accidental moving.
More
here.