A recent panel at the Digital Music Forum East showcased different tech and music luminaries discussing how social networks help people discover new music. Wired has summarized what the panelists had to say here.
One recurring theme is that social networks provide the quickness and convenience necessary to find and share music instantly. For instance, teens using the Last.FM plug-in can instantly recommend songs while they listen to MP3s, as well as let others track what they've been listening to. iLike's Facebook application lets users send each other public song dedications. Teens browsing the web over their phones can listen to the latest songs no matter where they are.
These technologies help teens establish themselves as tastemakers, as well as connect them to the tastes of their peers. It fits sharing music within the rhythms of their own complex social interactions.
Another interesting distinction is that social networks and music use differs between age groups. While older people who use social networks for music discovery might be looking for vetted recommendations from those "in the know" (which they might find on blogs and the algorithms of Pandora), teens are looking for the social interactions of passing along recommendations to each other and tapping into an aggregated listening experience.