Last I checked, the only thing you could do on Pinterest was like someone else's pin, or re-pin it. You couldn't comment or message or get to know people in any way (other than following their boards). It seemed more about things than people.
Now I see you can send a pin by email, share it on social, or even embed it. And there are comments available. I still don't see a way to message other users, but it's a start.
How do you use Pinterest? Do you consider it a social media site?