The Extensions/Install.py file is preventing install.

I added another clause as a workaround and it seems to work just fine:

root@epoz:/opt/intranet# diff parts/svn-products/qPloneComments/Extensions/Install.py  parts/svn-products/qPloneComments/Extensions/Install.py.orig
51c51
<     elif plone_version.startswith('2.5') or plone_version.startswith('3.0') or plone_version.startswith('3.1'):
---
>     elif plone_version.startswith('2.5') or plone_version.startswith('3.0'):

Thanks for posting your solution Erik!

Hope this gets fixed in the next release.