I haven't checked into Timeline much because I haven't had time. But it looks interesting and I will check it out at a later date.
So far, though, I'm not sure about whether or not I'll really get into it. It might be a little too much info for my taste.
But I would imagine the really creative types, like those who have created completley false identities on other social media, will have a blast with this.
Here's a link to mashable that shows how to enable Timeline.