Well, there will be an anonymous ‘always on’ setting—that’s the default state of browsing and downloading.
But as soon as you communicate with others (like in the commenting scenario describes) you are have to decide what level of disclosure of your identity you’re comfortable with in the given situation. This could be, say, by creating a one-time throwaway pseudonym ID, a persistent pseudonym, or an ID that discloses more about your actual identity. That’s entirely at your discretion.
These are elements of the User Experience Design, which aren’t directly covered in the fundamentals, but are part of the implementation of them; this is very much becoming our focus now as we move toward launch. There is no reason why it couldn’t be as simple to use as Google profiles for example, with the added bonus of not having to learn all new parameters, nor sift through privacy policies, for each new service you want to use.
I would argue that you probably aren’t, even if you go to really extreme lengths. But with the SAFE Network hidden tracks will be the default, with no extra effort on your part, and revealing your identity is a progressive disclosure, based on your individual requirements.