The biggest changes still to be done are:

http://www.gimp.org/source/

(changed to Git in master, waiting for the update)

and

http://www.gimp.org/source/howtos/stable-cvs-get.html
http://www.gimp.org/source/howtos/stable-cvs-build.html

both still referencing CVS.

This bug is now over a year old. (I ran into it when, on reporting bug 611176, I was asked to fix it myself, discovered that instructions on building GIMP from git were not available, and I was then asked to write them.)

So, new would-be developers will not be able to build GIMP from git, and will rapidly lose their enthusiasm for contributing or joining the happy little GIMP developer community, which has erected this as a barrier to entry.

Way to go, guys!

Asd I wrote in the other bug, help with re-writing the guides to build GIMP - especially from someone who has done without much prior knowledge about building software - is appreciated.

I guess that the documentation shouldn't try to be more elaborated than http://www.chromecode.com/2009/12/best-way-to-keep-up-with-gimp-from-git_26.html

That chromecode page doesn't explain what the dependencies are (babl? gegl?), describes an install prefix (not the suffix flag to make install?) and seems pretty useless to a layperson. Why would you do make install for a developer copy you're about to modify, and overwrite a release copy?

That page also presumes that the reader understands autoconf. Yeah, right.

From what I can tell, the page presumes that the reader reads it.

from that page
"I assume you know how to install necessary dependencies"
(which aren't listed, and need to be installed from source)
[..]
from comments:
"I am not sure how to follow the procedure you recommend."
"You make want to mention that you have to "git" babl and gegl as well as git"
(which is a lot beyond simply installing dependencies as rpms etc.)

That's covered in the last paragraph:

"The above approach works for as good as all GNOME projects, including GLib, babl, GEGL and GTK+. This makes it easy to adapt to GIMP's build requirements of these and other libraries even if your distro doesn't meet them. Let me know if you have problems!"

Then you should close this bug to prevent it cluttering up your database, rather than addressing it in any meaningful way.

The thing is that I'd prefer that the guide on www.gimp.org is rewritten only once, without becoming obsolete as soon as a dependency changes or someone tries this on a distro that lacks many dependencies. It's also nice that it can be easily adapted to describe a build of the stable branch (only the git url changes).

Using this description means that people have to read the whole document at least once before attempting a build (the docs teaches them how to build, and then tells them that this will work for others of GIMP's dependencies, too), but this hint can be added right at the beginning. 

In my opinion, one thing that should be made more clear in Martin's description is how the PREFIX environment variable is set - it points autoconf to the config.site, this is what prevents overwriting any system libraries (as well as placing them in /usr/local, which can have similar side effects).

We have http://www.gimp.org/source/howtos/gimp-git-build.html now, and http://www.gimp.org/source/ - I'm closing my old bug as fixed.