As rumored, Google Music launched its music store today with a range of new content partnerships, letting users buy millions of songs from the Google Marketplace. Sony Music Entertainment, Universal and its subsidiary EMI are launching with the revised service, bringing along their formidable music archives — notably missing, though, is Warner. There's also a host of independent labels on board, giving Google Music a total of 13 million tracks; 8 million of those are live today, with the rest coming soon.

Google's also working with the Rolling Stones, Coldplay, Busta Rhymes, Shakira, Pearl Jam, Dave Matthews Band and other artists to offer exclusive content, like six never-before-released concerts from the Rolling Stones. Busta Rhymes also released his latest album, "Why Stop Now," today exclusively on Google Music. It's part of a big artist-focused strategy for Google, and the company says it will be adding many more partners in the coming months.