[fakelvis]

There's also another way of making money from advertising: flat rate.

While I'm opposed to the idea of ads on HN, if it were to be implemented I can't imagine PG looking at CPI/CPC methods. Rather, I suspect advertising space would be 'rented' on a monthly basis for a much higher fee to technology companies, etc.

But I'll reiterate: I'm against advertising on HN for multiple reasons (poor revenue model for a community like this; there are better alternatives; I don't like them), and I would not be surprised if PG was too (although I've not way of knowing).