But using personally identifiable data for targeting (which facebook seems to be doing) is entirely different from doing personally identifiable targetting (which no one is doind). If all the information that leaves facebook servers is which ads to show then it's really difficult to argue that privacy is being breached.
Wait till they are using it to power security-cam equipped targeted video billboards on every bloody bus-stop. Which is the day I probably decide that we have failed as a species and go and live in a yurt somewhere in the woods with no electricity and live mostly on slightly burnt squirrel while designing a programming language based on the art of rearranging different piles of mud.
People may not be in a buying mood while on FB, but they will be on other sites.