Hey Paul,

I'll add to Suzy's comment by saying one of the important features about Pinterest is that each image that is pinned carries the original URL as a backlink. This is what made the site explode for marketing purposes.

Imagine you have created a series of images about your niche and posted them on your website or blog. By "pinning" them, and giving them tags that match the niche interest, people will discover them through search and drive traffic to your site!
Add to this the viral social bookmarking and re-pinning, and you've got a reason to create lots of rich image content.

About re-pinning: This is worthless as marketers, but fantastic for consumers. Repinning images will only bring traffic to your Pinterest board, but the actual image will still contain the original backlink. Better to host your own images and let the others do the repinning!

Hope that helps!
Cheers,
Nick