Examples of Large Datasets on Postgres?

The driving factor for me is that, in my local community college, where I am taking database classes, the (admittedly biased) Oracle pros who are teaching the classes keep referring to PostgreSQL as "light".  Even when I bring up the Yahoo example, they respond with, "I've never seen that".  While I can truly appreciate their bias (I am surely biased in quite the opposite direction), I think they need to be willing to acknowledge that their understanding of Postgres is limited.