Is my data private?
I will endeavor to keep your data private. I will not sell it or give it away without asking permission first. I will not spam your contacts, or use your data for my own purposes without getting permission from you.
Who can see my data?
The only people who should be able to see your data is you, and me (Jeff Dean). I have to see it as I fix bugs and add new features to the site.

However, since this site is in it's early stages, there might be a bug that allows other users to mistakenly see your data. I think the chances of that happening are low, but still, you should be aware that there's an off chance some other folks might see your data inadvertently.