Being able to use ${section:var} in other sections would be great to keep ini files DRY.

As tox incorporates a number of other features wrt to ini-file parsing we probably would need to implement the requested {section:var} feature ourselves. Want to give it a try?

For Python 2.6 and 2.7 there's a backport of configparser from 3.2:

http://pypi.python.org/pypi/configparser

I don't know how much that helps in Tox context.