having recently acquired a facebook, my current answer is probably an hour or two a week. My interaction with facebook is posting links of stuff I'm releasing (which, at the moment, has a target audience of people at my uni, when this project is more general, I'll post it on HN), answering friend requests, and answering messages posted to me.<p>Of those three, two of which I do after facebook sends me an email telling me either "hey, this guy requested to be your friend", or "hey, this guy sent you a message, here is the content: [...]".