Yahoo! official launched their online music subscription service today. Y! Music Engine is a competitor to iTunes and Napster. It has some nifty features such as the ability for others to write plugins to enhance it and the price is lower then the other competitors.
One distinction with Yahoo's service is that it is a subscription-based and rental-based. Users pay a monthly fee and have the ability to "rent" songs to listen or can choose to buy the songs for a price. Renting a song basically allows a user to have unlimited access to the songs and even share it with others through Y! Messenger, but he can't burn it to a CD or transfer it to whatever device he wants until he purchases the song for $.79 a song.