I saw an interview with Gary Vaynerchuck in the Nordic eCommerce summit and one of the things that stuck out for me was when he said that "Pinterest sells more wine for them than Twitter and Facebook combined"
The thing is if your revenues are up 2000% month-over-month and you start with $200 the next month you have $4000, then $80,000 etc. Those are pretty nice numbers very quickly.
According to the blog post, consumers are 10% more likely to buy vs. Facebook - well, that's a decent lift stat but it does, as someone else mentioned, depend on the base. Then, later in the article we learn that in Sept 11 they had 75 total orders (across 26,000 shops) via pinterest, then 320 orders in April 2012. Yes, that's more or less 4x the Sept number and does indicate an upward trend - but that's still a very, very small number, and the growth rate is unlikely to continue.
Pinterest is definitely interesting - I'll be trying it out for some eCommerce, but I'm not expecting much at this point.
... That's just from Shopify stores though. Most things people buy (and Pin) aren't sold on Shopify stores. All that data is good for is showing that it's increasing rapidly.