Just to clarify, the only data we would be sharing with the public is the reconstructed cell data, which involves no user information. All user information kept in our database or other HQ records is completely confidential unless you choose to publicize that information yourself in chat (e.g. you tell everyone your e-mail address) or you opt on the game to display what country you live in (by selecting a flag in your user settings). The only user information that Eyewire itself collects is what you supply at signup (username, password, e-mail address), what you supply us if you win swag (mailing address), and what we learn through occasional surveys to get a sense of our user base. We will never publish or sell user information to third parties; and even when we publish survey results, no information in those results can be linked to any specific users.
Please note that we do have the option of logging in to Eyewire using Facebook. If you are concerned about the Facebook login allowing Facebook to know that you are using Eyewire, then we can only recommend switching to "normal" login.
I hope this addresses your concern!