At the moment, we are still running Zope 2.7.2 and ZODB 3.2.3. I suspect that the upgrade to Zope 2.8.1 would be easier than the 2.6.x to 2.7.x migration (which was mostly the Python 2.2 to 2.3 and CMF 1.3 to 1.4 differences) but the upgrade task hasn't risen to the upper level of business priorities.