Public Credit reports & opting out

I got this email, and I need the straight dope on it:

I called the number and it gave me a couple of prompts and was asking some personal questions (i.e., phone number, ssn, name and address, etc.). Before I give this info to some annonomyous (sp?) computer, I would like to have it verified that this is legit.

Anyone know anything about this?

Snopes to the rescue!