This question ran through a 2012 conference in Berne at which I spoke. The conference marked the conclusion of the project "Development of Indicators to Evaluate Offerings and Performance in the Area of Education for Sustainable Development (ESD)", which ran from 2008 to 2011 with partners from Germany, Austria and Switzerland. The goal of this project was to present indicators that reveal the extent to which sustainability as an idea has been integrated into the education system on all levels of formal education, not only nationally but also in an international comparison. Tricky stuff, of course.
The papers and other background studies are now on-line here.