I noticed this earlier, but it was brought to my attention that I was stuck in post #666 and I needed to make another post.... so "Big" this one is for you!
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .