The good folks over at Ars Technica posted the following guidelines for privacy considerations on Facebook.  Excellent article covering everything from dividing your online "friends" into groups that reflect your real-life relationships to how to edit privacy settings for photos, videos, and even the ads.  Check it out:

http://arstechnica.com/web/news/2009/08/meshing-social-networking-and-privacy-on-facebook.ars