Bewenched - 5:04 am on Dec 9, 2012 (gmt 0)
It's not a download api call .... but you can write your own program that makes calls to the api, which gets product data of whatever query you want, you can even get the links to the images that anyone is using for their ads.
From that you can run another program or your own little home spun bot of choice to go fetch those images as you see fit.
And there's no way to limit who really gets the feed... you cant say sitex can use my data in their app, but not siteY.
Either you approve it for apps outside of google shopping or you dont it's black and white.