MySpace, Warner Music Group, Sony BMG, and Universal Music have announced plans to launch an online music web site called MySpace Music (not to be confused with the existing web site called MySpace Music, rather the new site will be a spinoff of MySpace’s existing service).

The music companies wil be making their complete content libraries available. Users will be able to stream ad-supported audio and video for free, or pay to download files includign songs and ringtones, MySpace Music will also sell concert tickets and artis merchandise.

EMI hasn’t signed onto the project yet, but the New York Times reports that sources say the 4th major label will probably join up soon.

The music labels will own a minority stake in the business, which will compete with Apple’s iTunes. Of course, the labels are making money through iTunes sales as well, but they’ve been complaining for a whlie that as the dominant online music retailer, Apple has too much control over the pricing and distribution of digital music.