I wanted to try and install the latest version of the GIMP So I googled and found this blog with a nice gimp svn download and installation script named gimpsvn.sh
cd ~/gimp-build
My notes:

Do make a directory such as gimp-build and cd into it
mkdir ~/gimp-build
cd gimp-build

When you copy the script from the website and paste the script into an editor you may need to remove the fancy quotes “ and replace them with plain old quotes " likewise some single quotes may show as these ’ so you may need to replace them with '. Also run through the script and check for bad line wraps as some of the commands may fail due to them.

I also create a my_prefix=/opt/gimpsvn variable at the top of the script and replace all instances of /opt/gimpsvn with $my_prefix to allow control of the location with only one change.

Save the script into your gimp-build directory as gimpsvn.sh and make it executeable chmod +x gimpsvn.sh

To kick the build off
./gimpsvn.sh


The gimpsvn.sh script uses checkinstall to install the packages. For package name I simply typed the name of each package: BABL, GEGL or GIMP and pressed enter twice. e.g.
Please write a description for the package.
End your description with an empty line or EOF.
>> GIMP
>>

I pressed enter to accept the rest of the checkinstall defaults:
Enter a number to change any of them or press ENTER to continue:

I entered no to create a docs package.
Should I create a default set of package docs? [y]: n

When seeing the checkinstall error "Building Debian package... FAILED!" I ignored it because the install into $my_prefix (/opt/gimpsvn) was successful, which is what counts

I entered no to view the log after checkinstall finished

Once all the packages are installed it's a good idea to create a gimp-2.5 launch script somewhere in your path.

I created /home/user/bin/gimp-2.5 with the following contents as recommended by the developer release notes and made it executeable.

#!/bin/sh
PREFIX=/opt/gimpsvn
PATH=$PREFIX/bin:$PATH
export PATH
LD_LIBRARY_PATH=$PREFIX/lib
export LD_LIBRARY_PATH
$PREFIX/bin/gimp-2.5 "$@"


This was all done on:

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 8.04
Release: 8.04
Codename: hardy