You may have heard about Facebook’s daring new Timeline project. If you haven’t, you will soon when it takes over your profile on October 2. For the uninitiated, Timeline is your entire life. On Facebook. Not only does it show you major events from the years you’ve been on Facebook, you can even go back and add seminal events to your timeline. Adorable baby pictures for “birth.” Your wedding, the day you got your dog, the day your child was born.

Not only is Facebook encouraging you to share every moment of your past, it’s making it easier to share your future. New applications encourage you to share the minutiae of your life, from what you cooked for dinner to what music you’re listening to on Spotify to every movie you watch. Live your life in the open, Facebook says. Share. Live. Join us.

As a marketer, I’m thrilled about the changes for the very reasons I personally fear the changes. It means that marketers like me will have access to all kinds of your information that will allow us to target ads, content and other information to you. This is fantastic, because it makes my job easier and helps me find and reach customers in my clients’ target demographics. It means we can use every aspect of your personality, your likes, dislikes and indeed, your entire life story to better sell you things. It’s a dream come true.

But I use Facebook personally, too. And I’m concerned. Concerned about the ever-shifting patchwork of privacy settings. Concerned about how Facebook tracks your movements online–even when you’re not logged into the site. Concerned that there really are no boundaries anymore between the public and the private, the personal and commercial.

Timeline isn’t necessary a bad thing. And Facebook isn’t necessarily evil. But think long and hard about Timeline and the role you want it to play in your life. Because there will be people like me out there, ready to use anything you share.

Update: The launch of Facebook Timeline has been pushed back until at least Tuesday, October 4, due to a pending lawsuit.