Here's how you can block search engines from displaying your public timeline in search results.
1. Click the arrow drop down menu in the upper right corner of the Facebook interface.
2. Click on Account Settings.
3. Click on the Subscribers link in the left nav bar.
4. Make sure the Subscriber Search checkbox is unchecked in the Subscribe Settings menu. If it is checked then search engines will be able to display your public timeline in search results.
Public posts are one thing, but having search engines find them and display them is quite another. So it's a good idea to make sure Subscriber Search is off on your Facebook account.