I did some research about automating pinning yesterday. If you take a look at their "Pin it" buttons you'll see it just does a POST request to a URL. Just do the same POST request.
Cross-domain POST is not possible with all browsers (I presume IE is the main culprit, as usual).
It accepts a GET
We aren't using an API to interface with Pinterest. It's just posting to the same url the pin bookmarklet does.
Roger. That's the same reverse engineering that other people are doing, thanks.