Just as before, the site offers unlimited free streaming of content posted to an artist's profile. But now its system for playlist creation and purchase has improved, especially now that the fourth and final big label is secured.

Social Network MySpace has officially launched its music-dedicated portal after securing EMI as its final partner among the Big Four major labels.

Songs can be queued into the MyMusic Player in the user's profile, or be purchased if thusly enabled. In BetaNews tests this morning, we could find very few artists that had enabled "buy" links. Featured artists the Jonas Brothers, for example, have a player embedded on Myspace Music's homepage that links to Amazon's MP3 store, but in their related profile, song purchasing was unavailable.

Tracks that can be purchased directly in the MyMusic player feature an Amazon Logo. When clicked, the player opens a confirmation window and prompts for Amazon.com login information. From that point, it works exactly like Amazon's MP3 store, launching the download client and funneling the album or song into your player of choice.

MySpace has also partnered with Jamster, adding the "find ringtones" search directly to the MyMusic player.

The player can be accessed independently of a user's profile or popped out into its own window that includes artist updates and advertisements. The player draws a close parallel to Last.FM in the "social playlisting" aspect where playlists can be made publicly viewable, each list can include up to 10 songs. Users can browse their friends' playlists or those featured by MySpace, which currently includes MySpace President Tom Anderson's own (mystifyingly combining Pussycat Dolls and Alice Cooper), and one dedicated to MySpace's upcoming "Secret Shows."

The site's launch was briefly delayed, causing speculation that the immense project was under antitrust scrutiny. These rumors, MySpace told BetaNews earlier, were unfounded, though the company did not give any clue at the time to the reason for the delay. At the time, however, the service still only officially had three of the four major labels as participants. Today's MySpace Music launch announcement simultaneously served to announce that straggling major EMI had joined the project.