I don't have any inside data, but I'm suspect Facebook's usage numbers for lists are quite low. Anecdotally, I'm the only person out of all my friends that uses

I don't have any inside data, but I'm suspect Facebook's usage numbers for lists are quite low. Anecdotally, I'm the only person out of all my friends that uses friend lists for anything (mostly to tailor privacy settings). Most people are unaware they exist. Secondly, Facebook auto-populates lists based on clusters of friends (e.g. a bunch of friends are in your current city, so Facebook might create an automatic list for that). Twitter can't do this bootstrapping, for obvious reasons (and if they tried I wouldn't be surprised if the clustering was poor quality). Also, at the end of the day, it doesn't matter how many ways to slice and dice your friends there are. Nothing will change the fact that Twitter is crap if 1) nobody knows who you are (you're just tweeting to an empty room), and 2) you haven't spent the time to follow the right people. One will note that Facebook puts everything into one algorithmic news feed.