This seems like a natural move for Pinterest, and due to the nature of its content I think the ads have the potential to be highly relevant to the user. Maybe long-tail products could get an even better channel to reach interested customers?
How about reversing it? Help users search through various products, using what you know they like as a guide. Find deals for them. Instead of collecting data on users and using it for advertisers, make vendors give you tons of data and use it for your users.
That is a very interesting idea. I am wondering if monetized recommendations can be done algorithmically, which might be the case with their interest graph. However, if not and they are targeting long-tail ads it might be better to follow googles lead and do something similar to adwords. Do you have an intuition on this?
If you're chasing long-tail, it might be better to do something like Pandora. Let people fill in aspects they like (or figure it out from their pins), then find products that fit the criteria. "We see you like sky-blue and polka dots. Here's a purse from a designer you've never heard of, all the people who like it, all the pinboards it appears on, and an exclusive 5% discount if you buy through this affiliate link."
