Hey Dana,
Here is a bit of explanantion right from the site:
Pin4Etsy's network of like minded Etsy store owners, fans, enthusiasts, customers and entrepreneurs joining forces to help each other is what we call "Petsy Power".
Here's how it works:
1) We make it simple to create a "well formed" pin that others in your niche want to re-pin. These pins will improve your stores ranking on Google and Pinterest's search algorithms.
2) Our network of users re-pin your pin in exchange for having their pins re-pinned. As a network member, you simply pin the pins that YOU want to pin.
Your pin is then pushed to the network until it is re-pinned the number of times equal to the number of pins you re-pinned.
What seems to be also good (of course it's still too soon t be sure) is that pintersest is also allowing Etsy sellers to eventually sell there products on there too, so it will be another avenue to gain possible sales.