One of the things that the new Facebook timeline will do is show you a history of your posts and pictures over time. I wonder how many people will be surprised to read their own social histories?
One thing that you can do to make sure that you are being authentic with your audience, is to periodically read your past posts and make sure that as a group they accurately represent who you are.
I just discovered a fun new tool for Twitter called mirror.me that creates a fun word puzzle out of all of my tweets to create a composite picture of what I’m taking about on Twitter. I was very surprised at how accurate it turned out to be.