Getting it installed, however, just about killed me. Here are the steps I finally puzzled out for Ubuntu 9.04. Miss any steps - or even change the order - and you'll get error messages that don't help even slightly.
sudo apt-get update
sudo apt-get install python-setuptools python-vtk
sudo easy_install -U numpy
sudo easy_install -U docutils sphinx TraitsBackendQt[nonets] AppTools[nonets]
[EDIT] If you're not on 9.04, or you just want to be on the safe side, it doesn't hurt to
sudo apt-get install python-dev python-qt4at the beginning of the whole process.
The other odd thing is that this lovely editor apparently has no name, and certainly no handy start script or presence in any menu. Mine got installed at
/usr/local/lib/python2.6/dist-packages/AppTools-3.3.0-py2.6.egg/enthought/rst/app.py; your best bet to find yours is probably
sudo updatedb; locate -r rst/app.py$
Then, set up a bash script to make it usable. I'm calling it "rsted".
sudo nano /usr/local/bin/rstedand fill it with:
python /usr/local/lib/python2.6/dist-packages/AppTools-3.3.0-py2.6.egg/enthought/rst/app.py $*
sudo chmod +x /usr/local/bin/rsted, and live happily ever after.
(The $* in /usr/local/bin/rsted doesn't actually do anything - the editor doesn't seem to accept arguments like a filename - but I'm being hopeful for the future.)