It's the type of thing twitter could really facilitate too - oh I see you added snoopdog and drdre, you might be interested in the "West coast Rappers" list! P

It's the type of thing twitter could really facilitate too - oh I see you added snoopdog and drdre, you might be interested in the "West coast Rappers" list! Publishing/maintaining lists is something a organisation could do - ie CNN might want to publish a list of all their political journalists. The list thing is really just a example of a feature they could have experimented with and for whatever reason didn't.