I was able to download the source code for version 2.7.0 at
ftp://ftp.gimp.org/pub/gimp/v2.7 without any problem.
Wow, that's really weird. My work computer can directly download it, and my home computer can directly download it, but when I use my home computer as a proxy at work, it can't access the server.
Thanks for all the help. It's definitely been a really cool ride so far getting used to Ubuntu, and I'm loving it so far.
So are you saying that I should just forget about 2.7 and wait till they finish 2.8 stable?
Pfff, it can't hurt to try. I don't recommend doing it by adding repositories unless you've really messed around with repositories before. Doing that is the equivalent of downloading random exe files in Windows and opening them. Chances are, you'll be fine, but sooner or later something bad could happen, then you have to deal with the fallout.
Here's the manly way to do it:
* Browse to
ftp://ftp.gimp.org/pub/gimp/v2.7/ and download the "gimp-2.7.4.tar.bz2" file.
* Expand the file either with your file manager or by visiting the directory in your terminal and typing "tar -jxf gimp-2.7.4.tar.bz2"
* In a terminal, visit the directory and type "./configure"
* If the above does not complain, type "make". Then after a big wall of text the program will be available in that specific directory tree, probably by typing "bin/gimp", since it'll likely be in the "bin" subdirectory, which is a name for where programs go.
* Past that, to actually put it on the system so it can be used globally and so it shows up in the app menus and so forth, "make install"
Chances are, the "./configure" step will yell about having the wrong version of something or other. For example, my opensuse 11.4 system at work had the wrong version of intltool. My archlinux system at home was missing the python source code -- when you install something from source, you need the source version of any libraries and such that it uses. This can make the whole process incredibly annoying. So, yeah, waiting might be a good idea, unless you just want to play around.
This is, in fact, the reason why Linux won me over with respect to software distribution in '00, having had to create what essentially was a free "app store" more than ten years before Apple did it. It was a desperately needed solution to a problem nobody wanted to deal with quite so often, and it frankly annoyed the crap out of me how primitive the process felt elsewhere for most of a decade.