Pinterest really has arrived: A survey from Experian Hitwise on Friday put the site at third on the list of most popular social networks, behind only Facebook and Twitter. The survey showed Pinterest with 104 million hits in March, according to Mashable's handy list (if you don't want to download Experian's whole report), after Facebook's seven billion and Twitter's 182 million. Linkedin came fourth with 86 million.

Last month, when Pinterest hired Facebook's former director of monetization, Tim Kendall, board member Jeremy Levine had told The Wall Street Journal, "My hope is that if we build a service that a lot of people use to plan and discover things, that will be really valuable." They've clearly now got the first part of that plan completed: Lots of people are using Pinterest. The second part is a bit more of an open question, but people clearly believe there's a lot of money to be made. The Atlantic's Alexis Madrigal estimated in February the site could generate $45 million a year from commissions from affiliate links. And way back in October the venture capital firm Andreseen Horowitz valued it at $200 million. This is already turning out to be the site's banner year, and it's not even June.