We added premium plans to EDU 2.0 for School about 9 months ago, and launched EDU 2.0 for Business (which has no free plan except for the 30-day free trial) about a year ago. Here are plots of the revenue growth for both companies (actual numbers are intentionally omitted):
EDU 2.0 for School:
EDU 2.0 for Business:
Overall, I'm very happy with the growth curves for both companies. It's too early to make any kind of accurate extrapolations, but our goal for 2011 is to increase the revenues for each company by at least 4x. At this point, this seems very doable, especially since we haven't done any marketing yet and the growth to-date has been 100% word of mouth.