Gimp 2.6 has some new dependencies (gegel, babl). I've patched various Portfiles and added some new ones (for gegl and babl).
And I just typed: "sudo pot install gimp"
So let's hope that everything compiles well...
I was about to start doing the same thing
I won't have much time until the week-end though, so if you come up with something before i have time to look into it, and you don't mind sharing, it would be great.
I'm not sure if the latest GEGL/BABL build out-of-the-box on mac. I know i submitted a few patches to them, and they integrated in SVN, but i don't know if they did another release since then.