jhbuild is a build system used by the GNOME project (and others) for building a
stack of modules (with interdependencies); see the jhbuild module in GNOME CVS.

It provides a relatively easy way to build the entire GNOME development stack on
a test machine and is very useful for getting new hackers involved in GNOME.

It would be awesome to have a jhbuild plugin for Eclipse, I think it would be a
big boon for Eclipse in the GNOME community.

File->New Project->Software Stack (jhbuild)
You would then let the user choose from a list of modulesets (e.g. GNOME 2.8,
GNOME 2.10, GNOME 2.12 etc).
jhbuild can grab modules from CVS, or from tarballs as necessary.
The UI could show all of the modules in the moduleset, build them as
appropriate. You could build individual modules, or all of the dependencies of a
module.

(typically you want to make local modifications to the moduleset, e.g. when
adding gnome-keyring support to evolution, I'll want to add that dependency in
the moduleset graph). 

Ideally there would be a verb to "Run" the moduleset, which would pop up an
Xnest window with the built-with-jhbuild gdm login prompt running in it; you
would be able to set breakpoints in the whole of the desktop.