We've listened to a German podcast with one of gimps main developers, Sven Neumann, today, have searched the web and read all the mails of the developers mailing list. Although the roadmap for GIMP 2.6 is not yet finalized it is already clearly visible what GIMP 2.6 aims for. Below we've listed some of the top goals the devlopers want to achieve with the next version:
There are two main parts in the 2.5 developement branch that is being worked on: the GIMP's internal core and the graphical User Interface. 2.4 already has set the course for the future of GIMP and so does GIMP 2.6. By connecting and replacing some GIMP core code with the advanced "Generic Graphics Library" (GEGL - http://www.gegl.org), which will be a long and difficult process, the developement team sets the course for future non destructible image manipulation capabilities in GIMP.
For those that don't have a clue what GEGL is / can do - here's a short example: GEGL offers graph based non destructible image manipulation - which means following: original pixel regions are not being altered by a certain operation. assume you're doing a color correction on a photo, then you work another hour on that photo appliing lots of other filters. After all operations you can still change the first color correction operation because the original pixel information has not been altered. You don't have to redo all the steps or go back in the journal.
The second main point being worked on is the user interface. One of the most annoying things for lots of users is the many windows you've to deal with when working with GIMP, it sometimes just interrupts the workflow. The developers are trying a solution where tools and other windows can 'dock' at the main image window. Finally it should be then possible to have only one window open in the task bar, which make life easier for many of us. This is the goal. We're all anxious to see the developement on this!
From a user perspective of view we shouldn't expect too many 'visible' changes when GIMP 2.6 arrives. Because of the implementation of GEGL much code has to be rewritten for the future, which will take most of the developement time.
Nothing final yet but here are some other things that will be also worked on: It is planned to make the IWarp filter a tool, "smudging" will be accessible from all paint tools and the jitter functionality will maybe also be available from the paint tools.
The vector layers will probably not make it into the 2.6 release, also it is unclear if 16bit colors per channel support or native CMYK support will make it into the next release but we can at least hope for it ;-)
The upcoming stable versions are aimed to be released in a 6 months cycle. The dev-team wants to do more smaller steps than only a few big ones. That has been decided to bring the new features faster to users. So that means for us we can expect GIMP 2.6 somewhere in late spring / ealry summer - ah, and thats 2008 not 2009 of course, heh ;-)