Ask HN: How to build site directories at schools where social network launches?

Currently developing a social directory that will make connecting to your social network a snap. Fun+Easy+Powerful. Of course, a great product is only the beginning. We need the right users in the right places at the right times.

Should I have completely different directories for each school (college/university/high school) that I allow? For instance, should I allow users at Harvard to immediately search user profiles at Princeton?

Or not. Maybe, as a startup strategy, I should build completely different (mirror) sites for each university area and ask each user to select a school at login.