I doubt it was a 'response' per se. MIT OCW has been going for 10 years, whereas Stanford's offerings are more recent (from 2008, I believe).
Perhaps they've been encouraged to say something publicly about existing plans, since profs at Stanford have just opened a slew of new courses from next Jan onwards.
Aside: It would be really interesting to know how the profs at MIT felt about the Stanford courses. AFAIK, Stanford wasn't 'officially' involved in the online courses and it was primarily driven by the profs themselves.
http://www.ai-class.org/
http://www.ml-class.org/
http://www.db-class.org/ and more to come in January.
I took part in two of them and it was a great experience, so I welcome the competition :-)