Ok after looking around, I found a problem where someone said another install of ipython might be causing problems. enpkg is trying to install ipython 1.1.0 but I still had 0.13.1 around. So I removed it via:
$ sudo rm -rf /Library/Frameworks/EPD64.framework/Versions/7.2/lib/python2.7/site-packages/ipython-0.13.1-py2.7.egg
Then it loaded with errors about kernmagic so:
$ sudo enpkg kernmagic
It somehow re-installed ipython 1.0
$ ipython
Python 2.7.2 |EPD 7.3-2 (64-bit)| (default, Sep 7 2011, 16:31:15)
Type "copyright", "credits" or "license" for more information.
IPython 1.0.0 -- An enhanced Interactive Python.
So simply re-trying the enpkg command installs the latest version.
$ sudo enpkg ipython
prefix: /Library/Frameworks/EPD64.framework/Versions/7.2
ipython-1.0.0-2.egg [removing]
12.84 MB [.................................................................]
Jinja2-2.6-2.egg [removing]
1.58 MB [.................................................................]
tornado-2.2-1.egg [removing]
1.42 MB [.................................................................]
tornado-3.1.1-1.egg [installing]
2.16 MB [.................................................................]
Jinja2-2.7.1-1.egg [installing]
1.62 MB [.................................................................]
ipython-1.1.0-6.egg [installing]
12.92 MB [.................................................................]
$ ipython
Python 2.7.2 |EPD 7.3-2 (64-bit)| (default, Sep 7 2011, 16:31:15)
Type "copyright", "credits" or "license" for more information.
IPython 1.1.0 -- An enhanced Interactive Python.
And now it runs without errors. So, hopefully that helps anyone else coming across these kinds of problems.