Yea that stuff is totally blocked out of my mind. I use Facebook to connect with my friends and family, and will share a link occasionally if it really pertains to me. For the most part, though, I don't like spamming mass amounts of data to friends. The only benefit I see to things like delicious and other "social bookmarking" tools is the fact that they're "up in the cloud", aka, backed up somewhere away from my browser config folder.
Has anyone noticed the new Mahalo-esque stuff they're doing? All of your hobbies, movies, music, etc... that they're making part of this social graph is now linked together a lot better.
Example, one of my interests (for fun) is "underwater basket weaving" which now links to a page like this, http://www.facebook.com/#!/pages/Underwater-basket-weaving/1...
"Our goal is to make this Community Page the best collection of shared knowledge on this topic. If you have a passion for Underwater basket weaving, sign up and we'll let you know when we're ready for your help."
Pretty crazy.