The (not so) nightly builds of GtkRadiant have not included the Linux version in quite some time. The most recent available (2006-03-02) is missing many features, including the bobtoolz plugin. However, it is possible to compile it yourself.
I recommend you have a working install of the GtkRadiant 1.5 before trying to roll your own. See GtkRadiant1_5-Linux for instructions.
The source repository is located at https://zerowing.idsoftware.com/svn/radiant/GtkRadiant/trunk/ . To get the latest source, we use Subversion (known as svn):
svn checkout https://zerowing.idsoftware.com/svn/radiant/GtkRadiant/trunk/ ./GtkRadiant
Now we will compile GtkRadiant.
cd GtkRadiant
scons SETUP=0
GtkRadiant's default build settings create unoptimized, debugging executables. These are much slower compared to release builds, particularly when loading textures and during q3map2 radiosity. To create an optimized build, replace the scons command above with
scons SETUP=0 BUILD=release
If you want even further optimizations, edit lines 175 and 176 of the SConstruct file to read
CXXFLAGS += '-O2 -march=i686 '
CCFLAGS += '-O2 -march=i686 '
Other GCC options can go there too. If you are unsure about this, don't do it.
The documented way of installing gtkradiant is to run
python install.py
However, I just copy the 'install' directory and run radiant.x86
At this point you should have a working GtkRadiant build from the latest source. The development mailing list and other links can be found at http://zerowing.idsoftware.com/ These instructions are based off the COMPILING file that is included with the source.