There is so much unhelpful junk out there on the web when you do a Google search on synchronizing your Facebook status' with Twitter. So, a quick post.
If you want your Facebook status to auto-tweet, go to http://www.facebook.com/twitter/
If you want your Tweets to auto-Facebook-status-update (why is there no verb for this?), go to http://apps.facebook.com/twitter/
It's just a slight change in the sub-domain. You don't need any 3rd part software or other service. Facebook and Twitter worked this out among themselves already.