When I did my thesis on Facebook Pyschology way back when. One of the areas I studied was the communication of Cultural Capital through Social Networks. Basically Sociologist Bourdieau came up with a theory that suggested that people were analysed on three criteria – their Social, Cultural and Economic Capital (read more here).
Social Capital is how valuable you are in terms of who you are friends with and how they can help out the person analyzing you. In terms of Social Networks, it was judged in two ways through Social Networks. First being how many friends you have and then who those friends were.
People have realized the power of this form of capital and have often tried to game it. With Twitter this has happened with a number of spammers running script so that they can inflate the number of followers they have (check the Top 100 Twitterers in Australia – you will see some questionable people in there). However one thing that helps people evaluate someones Social Capital on Twitter is lists, the number of lists that someone is in, usually gives a good indication whether they are gaming twitter or not.
Although lists seem useless to most, they do have their role in reference checkings someones Social Capital at the very least.