Music networking as a function of learning "what's good"

This semester, for my course Digital Media Entrepreneurship, I need to become an expert in some technological aspect. I've chosen music sites that operate by taking in user preferences to determine what people like, and what can be recommended based on other users' preferences. My original idea was to focus on Last.fm, a UK-based site that is my personal favorite for music discovery, widgets and networking based on taste in music. Options within Last.fm are more plentiful than any other site I've come across. One can download a simple program that allows for "scrobbling," or the taking in of data (songs) that are both played in iTunes and on the iPod. Upon scrobbling, Last.fm collects the songs and artists played and creates numerical charts that can be posted as self-updating widgets on virtually any other site with weekly charts tallying up a user's most popular artists.

A topic I'm interested in pursuing is how sites like Last.fm work with others, namely major label dreamboat Rhapsody. An intriguing part of the online music world is that people want all of their listening connected, their charts accounting for all music listened to, so as not to create a bias. This results in many users developing their own ways of connecting the sites. A simple Google search will render results on how to scrobble music from one's personal Rhapsody feed into Last.fm, and do the same with sites like HypeMachine.