I guess adding pycomicvine to the package didn't make it as standalone as I thought.
This error is showing that you need the simplejson module for python installed.
I will see what I can do to either remove the external dependencies or bundle them in the plugin distribution, but in the mean time you should be able to fix this by installing the "simplejson" and 'python-dateutil' modules.
I can't tell which OS you are running under. On a debian / ubuntu based box you can get everthing installed using:
sudo apt-get install python-simplejson python-dateutil
For a more generic method you can use the instructions here to setup easy_install (part of the setuptools package)
http://pythonhosted.org/distribute/easy_install.html
Then you can use:
easy_install simplejson
easy_install dateutil
Sorry for the inconvenience, I'll try and get a fixed version out ASAP.