According to Daniel Sone in Washington DC and several others who chimed in to support his post, "Basically, anything using cloud-based storage through Amazon is down. 17hats, shootproof, netflix, wave apps, sign now, etc."
To my knowledge, I have no Amazon cloud, but I don't know who might be using them in the background. Yesterday I'd had trouble with M&T bank, posting to the Zenfolio gallery and my Wordpress blog. The blog is hosted by Network Solutions, but who knows where they get additional cloud storage?
So fair warning to all of us, if we're having troubles with online services or storage, consider our backup procedures, especially financial and photographic.