Following its purchase by Facebook a few months ago, Instagram released last Monday 12/17/2012 an updated version of its privacy policy and terms of service that involves severe changes affecting everyone who publish their pictures on this huge social network wich a few months ago beat 100 million users.
As of January 16, 2013, all new pictures uploaded to Instagram may be sold to others and they have no obligation to compensate you for it, or even notice to you. That means for example that your photos, whether a landscape, a monument or yourself, may appear in any advertisement or as a part of the cover of a magazine.